A on the wall of the Drachenschlucht Eisenach, Germany

A is the first letter of the Latin alphabet. It can also refer to the following. Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... Image File history File links A-Character. ... Image File history File links A-Character. ... Eisenach is a city in Thuringia, Germany. ... For other uses of A, see A (disambiguation). ...

Science

• In astronomy,
  • A stands for a whitish-blue class of stars in the Morgan-Keenan system.
  • A stands for a January 1 through 15 discovery, in the provisional designation of a comet (for example, C/1760 A1, the Great Comet of 1760) or asteroid (for example, (4099) 1988 AB₅).
  • As a comet designation prefix, indicates an object that was at first mistakenly identified as a comet, but is actually a minor planet (for example, A/2005 JM₃).
  • a is often used to denote the semi-major axis of an orbit.
• In biochemistry, A is the symbol for the nitrogenous nucleic acid base adenine, and also for alanine and adenosine.
• In electronics,
  • A is a standard size of battery.
  • A refers to the anode, or filament, component of a vacuum tube.
• In genetics:
  • Haplogroup A (mtDNA), a human mitochondrial DNA (mtDNA) haplogroup.
  • Haplogroup A (Y-DNA), a Y-chromosomal DNA (Y-DNA) haplogroup.
• In medicine, A (also, A+ or A-) is one of the human blood types.
• In nutrition, A is a vitamin.
• In physics, A is the center of a hexagonal face of the Brillouin zone of a hexagonal lattice.

For other uses, see Astronomy (disambiguation). ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... Template:Non-Periodic Comet The Great Comet of 1760 was seen on 7th January 1760 by Abbe Chevalier at Lisbon. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... Biochemistry is the study of the chemical processes and transformations in living organisms. ... Look up nucleic acid in Wiktionary, the free dictionary. ... Adenine Guanine Thymine Cytosine ... This article or section does not adequately cite its references or sources. ... Alanine (Ala, A) also 2-aminopropanoic acid is a non-essential α-amino acid. ... Adenosine is a nucleoside comprised of adenine attached to a ribose (ribofuranose) moiety via a β-N9-glycosidic bond. ... This article is about the engineering discipline. ... Four double-A batteries In science and technology, a battery is a device that stores energy and makes it available in an electrical form. ... Symbols representing a single Cell (top) and Battery (bottom), used in circuit diagrams. ... Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ... This article is about the general scientific term. ... In human genetics, Haplogroup A is a human mitochondrial DNA (mtDNA) haplogroup. ... In human genetics, Haplogroup A (M91) is a Y-chromosome haplogroup. ... Medicine is the science and art of maintaining andor restoring human health through the study, diagnosis, and treatment of patients. ... This article is about human blood types (or blood groups). ... The updated USDA food pyramid, published in 2005, is a general nutrition guide for recommended food consumption for humans. ... Retinol, the animal form of vitamin A, is a yellow fat-soluble, antioxidant vitamin important in vision and bone growth. ... Retinol (Vitamin A) For the record label, see Vitamin Records A vitamin is an organic compound required in tiny amounts for essential metabolic reactions in a living organism. ... This is a discussion of a present category of science. ... In mathematics and solid state physics, the first Brillouin zone is the primitive cell in the reciprocal lattice in momentum space. ...

Physical and chemical quantities and units

In physics and chemistry, the following quantities or units are abbreviated by the letter "a" or "A": This is a discussion of a present category of science. ... For other uses, see Chemistry (disambiguation). ...

• lower case, italic, boldface
  • acceleration, a (upper-case for an initial/constant accleration value; lower case for an instantaneous acceleration variable)
• lower case, italic
  • absorption coefficient, a
  • activity, a
  • hyperfine coupling constant, a
  • specific surface area, a
  • thermal diffusivity, a
  • the unique, or one of the, unit cell length(s), a
  • one of the van der Waals coefficients, a
  • Bohr radius, a₀
• lower case, upright (latin)
  • adsorbed, a
  • are, a, the deprecated symbol for the unit of surface area equal to 100 square metres
  • atto, a, the SI prefix meaning 10⁻¹⁸
  • year, a, from the Latin annum, especially in geology, archeology and astronomy; as prefixed with Mega (Ma) or Giga (Ga) to indicate periods of time.
• capital, italic, boldface
  • magnetic vector potential, A
• capital, italic
  • absorbance, A
  • absorption intensity, A
  • affinity of reaction, A
  • area, A
  • Einstein transition probability, A
  • Helmholtz energy, A
  • hyperfine coupling constant, A
  • mass number, A
  • nucleon number, A
  • pre-exponential factor, A
  • radioactive activity, A
  • rotational constant, A
  • spin-orbit coupling constant, A
  • van der Waals-Hamaker constant, A
  • Hall coefficient, A_H
  • relative atomic mass, A_r
• capital, upright
  • ampere, the SI base unit of electric current

Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point. ... The absorption coefficient is a property of a material. ... Look up Activity on Wiktionary, the free dictionary Activity may refer to— in chemistry, the effective DU BIST DUMMconcentration of an ion or other solute for the purposes of chemical reactions and other mass action. ... Scratches, represented by triangular shaped grooves, make the surface area bigger Specific surface area is a material property of solids which measures the total surface area per unit of mass[1], solid or bulk volume[2], or cross-sectional area[3]. It is a derived scientific value that can be... In heat transfer analysis, thermal diffusivity (symbol: ) is the ratio of thermal conductivity to heat capacity. ... In the Bohr model of the structure of an atom, put forward by Niels Bohr in 1913, electrons orbit a central nucleus. ... In chemistry, a molecule is adsorbed onto a surface when temporary bonds are formed between the surface and the molecule. ... An are (symbol a) is a unit of area, equal to 100 square meters (10 m × 10 m), used for measuring land area. ... A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ... Atto- (symbol a) is an SI prefix to a unit and means that it is 10-18 times this unit. ... An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol) to form a decimal multiple or submultiple. ... A year (from Old English gÄ“r) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Annum is a Latin noun meaning year. ... This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... Archaeology or sometimes in American English archeology (from the Greek words αρχαίος = ancient and λόγος = word/speech) is the study of human cultures through the recovery, documentation and analysis of material remains, including architecture, artefacts, biofacts, human remains, and landscapes. ... For other uses, see Astronomy (disambiguation). ... In physics, the magnetic potential is a method of representing the magnetic field by using a potential value instead of the actual vector field. ... In spectroscopy, the absorbance A is defined as , where I is the intensity of light at a specified wavelength λ that has passed through a sample (transmitted light intensity) and is the intensity of the light before it enters the sample (or incident light intensity). ... Area is a physical quantity expressing the size of a part of a surface. ... It has been suggested that this article or section be merged into Helmholtz energy. ... The mass number (A), also called atomic mass number (not to be confused with atomic number (Z) which denotes the number of protons in a nucleus) or nucleon number, is the number of nucleons (protons and neutrons) in an atomic nucleus. ... The mass number (A), also called atomic mass number or nucleon number, is the number of protons and neutrons in an atomic nucleus. ... In chemical kinetics, the frequency factor or A factor is the pre-exponential constant in the Arrhenius equation, which indicates how many collisions between reactants have the correct orientation to lead to the products. ... The rigid rotor is a mechanical model that is used to explain rotating systems. ... In reference to a certain isotope of a chemical element, atomic mass (though also called relative atomic mass and atomic weight) is the mass of one atom of the isotope expressed in units (atomic mass unit, amu) such that the carbon-12 isotope has an atomic mass of exactly 12. ... Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current. ... The SI system of units defines seven SI base units: physical units defined by an operational definition. ... Electric current is the flow (movement) of electric charge. ...

Mathematics and logic

• A stands for area of geometric figures.
• A is often used as a digit meaning ten in hexadecimal and other positional numeral systems with a radix of 11 or greater,
• In blackboard bold, (U+1D538 in Unicode) sometimes represents the algebraic numbers.
• In the On-Line Encyclopedia of Integer Sequences, each sequence has an ID consisting of the letter A and six base 10 digits.
• In logic,
  • The letter A is used as a symbol for the universal affirmative proposition in the general form "all x is y." The letters I, E, and O are used respectively for the particular affirmative "some x is y," the universal negative "no x is y," and the particular negative "some x is not y." The use of these letters is generally derived from the vowels of the two Latin verbs affirmo (or AIo), "I assert," and nego, "I deny." The use of the symbols dates from the thirteenth century, though some authorities trace their origin to the Greek logicians.
  • In symbolic logic, the symbol ∀ or (an inverted letter A) is the universal quantifier.

In mathematics and computer science, a numerical digit is a symbol, e. ... 10 (ten) is an even natural number following 9 and preceding 11. ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. ... A numeral is a symbol or group of symbols, or a word in a natural language that represents a number. ... The radix (Latin for root), also called base, is the number of various unique symbols (or digits or numerals) a positional numeral system uses to represent numbers. ... An example of blackboard bold letters. ... The Unicode Standard, Version 5. ... In mathematics, an algebraic number relative to a field F is any element x of a given field K containing F such that x is a solution of a polynomial equation of the form a0xn + a1xn−1 + ··· + an −1x + an = 0 where n is a positive integer called... The On-Line Encyclopedia of Integer Sequences (OEIS) is an extensive searchable database of integer sequences, freely available on the Web. ... Logic (from Classical Greek λόγος logos; meaning word, thought, idea, argument, account, reason, or principle) is the study of the principles and criteria of valid inference and demonstration. ... For other uses, see Latin (disambiguation). ... It has been suggested that Verbal agreement be merged into this article or section. ... Mathematical logic is a discipline within mathematics, studying formal systems in relation to the way they encode intuitive concepts of proof and computation as part of the foundations of mathematics. ... In predicate logic, universal quantification is an attempt to formalise the notion that something (a logical predicate) is true for everything, or every relevant thing. ...

Computing

• As a programming language, A may refer to:
  • A-0 programming language
  • A Sharp (Axiom)
  • ARITH-MATIC
  • BASIC A+
• <a> is the HTML element for an anchor tag.
• In the Mac OS, Command-A (for All), and in Windows, Ctrl-A, and selects all the text in the document, or all the pixels of an image.
• A sometimes represents the set of all alphabetic characters within string patterns.
• A: is the conventional address of the first floppy disk drive in CP/M-based operating systems such as DOS.
• A is a security division ("Verified Protection") in the TCSEC.

A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. ... For A0 the ISO 216 specification for paper, see paper size. ... A# (A sharp) is an object-oriented functional programming language distributed as a separable component of Version 2 of the Axiom computer algebra system. ... You may have been looking for arithmetic, a branch of mathematics. ... BASIC A+ was developed by Optimized Systems Software of Cupertino, California, USA, to provide the Atari 8-bit family with an extended BASIC compatible with, but faster than, the simpler ROM-based Atari BASIC. While Atari BASIC came on an 8 KB ROM cartridge, BASIC A+ was delivered on floppy... In computing, an HTML element indicates structure in an HTML document and a way of hierarchically arranging content. ... In various branches of mathematics and computer science, strings are sequences of various simple objects (symbols, tokens, characters, etc. ... CP/M was an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. ... // An operating system (OS) is the software that manages the sharing of the resources of a computer. ... Instructions on how to use the directory command. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

The arts

• In fiction, the letter worn by Hester Prynne marking her as an adulteress in the Nathaniel Hawthorne novel The Scarlet Letter was an A.
• In film:
  • A is an Italian film made in 1969.
  • "A" is a Kannada movie directed by Upendra.
  • A (Rating), in the CBFC system.
  • In India, A is a movie rating, given to those intended to be seen only by adults.
• In music:
  • A (album), an album by progressive rock band Jethro Tull.
  • A, an album by Cass McCombs.
  • A (band), a British alternative rock band.
  • A Band, an experimental group.
  • A (song), Ayumi Hamasaki's 10th single.
  • A (musical note), the sixth musical note.
  • A (song), a song by the band Barenaked Ladies.
  • A, or "side A," refers to the top or first side of a vinyl record.
• In poetry, A is the major work of influential twentieth century author Louis Zukofsky.

For other uses, see Fiction (disambiguation). ... Nathaniel Hawthorne (born Nathaniel Hathorne; July 4, 1804 – May 19, 1864) was a 19th century American novelist and short story writer. ... This article is about the 1850 book. ... “Moving picture” redirects here. ... Upendra (Kannada:ಉಪೇಂದ್ರ) is a professional movie director, actor and script writer in the south Indian Kannada film industry. ... The Central Board of Film Certification or CBFC is the regulatory film body and censor board of India. ... A is an album by Jethro Tull. ... A is a Cass McCombs album released on May 20, 2003 on Monitor Records. ... Cass McCombs Cass McCombs is an American musician whose styles range from the anxious dronals of the Velvet Underground to lonesome hollowed out basement folk with many turns in between. ... This article does not cite any references or sources. ... A Band were a British musical collective formed in Nottingham in the late 1980s. ... A is the tenth single released by Ayumi Hamasaki on August 11, 1999. ... La or A is the sixth note (submediant) in the C Major scale. ... Barenaked Ladies (often abbreviated BNL or occasionally BnL) is a Canadian alternative rock band currently composed of Jim Creeggan, Kevin Hearn, Steven Page, Ed Robertson, Tyler Stewart, and formerly Andy Creeggan. ... A gramophone record, (also phonograph record - often simply record) is an analog sound recording medium: a flat disc rotating at a constant angular velocity, with inscribed spiral grooves in which a stylus or needle rides. ... This article is about the art form. ... The cover of the 1978 edition of Zukofskys long poem A. Louis Zukofsky (January 23, 1904 – May 12, 1978) was one of the most important second-generation American modernist poets. ...

Languages

• A, an, the indefinite article in English.
• In French,
  • a is the Third person singular conjugation, Present tense of the verb avoir: «il a»="he has".
  • à is a conjunction meaning either "with", "at", or "to": «à la carte», «à moi»; although «au» is used in place of «à le» (for masculine singular nouns) and «aux» is used in place of «à les» (for plural nouns).
• In Spanish, a means to or towards.
• In Portuguese, it is either the feminine definite article or a preposition meaning "to", "toward".
• In Greek, a- is a prefix (alpha privativum) meaning "not" or "devoid of," used in many borrowed words in English, German and Romance languages (for example, amoral, asexual, arhythmic).
• A (kana), the Japanese kana あ and ア which may be used to represent Asia.
• In Esperanto as well as in Ido, -a is the adjectival/attributive ending; A is commonly an abbreviation meaning English (language).
• In Interlingua, a means at or to.

Look up a in Wiktionary, the free dictionary. ... Grammatical person, in linguistics, is deictic reference to the participant role of a referent, such as the speaker, the addressee, and others. ... In linguistics, conjugation is the creation of derived forms of a verb from its principal parts by inflection (regular alteration according to rules of grammar). ... The present tense is the tense (form of a verb) that is often used to express: Action at the present time A state of being A habitual action An occurrence in the near future An action that occurred in the past and continues up to the present There are two... In linguistics, grammatical gender is a morphological category associated with the expression of gender through inflection or agreement. ... Definite Article is the title of British comedian Eddie Izzards 1996 performance released on video and CD. The video/DVD and CD performances were both recorded on different nights at the Shaftesbury Theatre in London, England. ... It has been suggested that this article or section be merged with adposition. ... In linguistics, a prefix is a type of affix that precedes the morphemes to which it can attach. ... The privative a (also known as privative alpha or α privativum) is the prefix a-, called a privative, which expresses negation (e. ... The English language is a West Germanic language that originates in England. ... The Romance languages (sometimes referred to as Romanic languages) are a branch of the Indo-European language family, comprising all the languages that descend from Latin, the language of the Roman Empire. ... あ in hiragana or ã‚¢ in katakana (romanised a) is one of the Japanese kana that each respresent one mora. ...   is the most widely spoken constructed international auxiliary language. ... Ido (pronounced ) is a constructed language created with the goal of becoming a universal second language for speakers of different linguistic backgrounds as a language easier to learn than ethnic languages. ... Interlingua is an international auxiliary language (IAL) published in 1951 by the International Auxiliary Language Association (IALA). ...

Other

• In American Major League Baseball,
  • The Oakland Athletics are often simply referred to as the "A's."
  • A can stand for Appearances or Assist.
• In calendars, A is often an abbreviation for the months April and August.
• In education, a grade of A typically represents the highest score that students can achieve. This is sometimes coupled with a plus/minus sign, as in A+ or A-, or a number, as in A1. It is occasionally a grade one level below A* (pronounced "A Star"). In Columbia, Finland, and New Zealand, A is the grade above a fail.
• In finance, A is the U.S. ticker symbol for Agilent Technologies.
• In games, the letter A is used to mark each of the Aces in a deck of playing cards.
• In international licence plate codes, A stands for Austria.
• In international paper sizes, A is a series of sizes with an aspect ratio of roughly 70% width to height, with A4 being an example popular size.
• In photography, most SLR cameras use A to signify aperture priority mode, where the user sets the aperture and the camera determines the shutter speed.

A in the Anarchist Symbol

• In political theory, an A in a full circle is an anarchist symbol.
• As the first letter of a postal code,
  • In Canada, A stands for Newfoundland and Labrador.
• In radio,
  • the NATO A band ranges below 0.25 GHz.
• On the serial numbers of United States dollars, A identifies the Federal Reserve Bank of Boston.
• In some sports, A is an abbreviation for Assists.
  • A is also a term used to signify the standard of grade a certain team is in comparison to another team of the same age. e.g. John is in the A team for soccer.
• In Christian theology, alpha is a metaphor for the beginning/creation of time and matter. It is sometimes translated to A.
• As a timezone, A is the military designation for Coordinated Universal Time+1, also known as CET or Central European Time.
• Topographically, A is used to describe an object shaped like the capital letter A, such as an A-frame.
• A (New York City Subway service), a service of the New York City Subway.
• A is a brassiere cup size.
• A name intended for a Swedish child born in 1991.

MLB and Major Leagues redirect here. ... Major league affiliations American League (1901–present) West Division (1969–present) Current uniform Retired Numbers 9, 27, 34, 42, 43, (As) Name Oakland Athletics (1968–present) Kansas City Athletics (1955-1967) Philadelphia Athletics (1901-1954) (Referred to as As) Other nicknames The As, The White Elephants, The... Appearances (2008) Starring The Voice Talents Of: Leon, Tom Cruise, Russell Crowe, Lisa Kudrow, Oliver Martinez, Michael Keaton, Billy Connolly And Ernie Sabella From: DreamWorks Animation ... See also: Assist (sports) ASSIST (the Assembler System for Student Instruction and Systems Teaching) is an IBM System/370-compatible assembler and interpreter developed in the 1970s at Penn State University by John Mashey. ... A page from the Hindu calendar 1871-72. ... Look up Month in Wiktionary, the free dictionary. ... This article does not cite any references or sources. ... This article is about evaluation of school work. ... Addition is one of the basic operations of arithmetic. ... In mathematics, subtraction is one of the four basic arithmetic operations. ... This article does not cite any references or sources. ... A stock symbol or ticker symbol is a mnemonic used to uniquely identify publicly-traded shares of a corporation on a particular stock market. ... Agilent Technologies NYSE: A is the actual descendant of the instrument company founded by Bill Hewlett and Dave Packard in 1939. ... Tug of war is an easily organized, impromptu game that requires little equipment. ... This article does not cite any references or sources. ... For the Russian group of artists, see Jack of Diamonds (artists). ... This is a list of vehicle country identification codes: Contents: Top - 0–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Note * Non-official Note1  There are other, unofficial codes in common... Comparison of the most common paper sizes. ... Comparison of the most common paper sizes. ... Photography [fÓ™tÉ‘grÓ™fi:],[foÊŠtÉ‘grÓ™fi:] is the process of recording pictures by means of capturing light on a light-sensitive medium, such as a film or electronic sensor. ... Cross-section view of SLR system: 1) Lens 2) Mirror 3) Shutter 4) Film or sensor 5) Focusing screen 6) Condensing lens 7) Pentaprism 8) Eyepiece The single-lens reflex (SLR) is a type of camera that uses a movable mirror placed between the lens and the film to project... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Anarchism is a generic term describing various political philosophies and social movements that advocate the elimination of hierarchy and imposed authority. ... The Politics series Politics Portal This box:      Political Science is the field concerning the theory and practice of politics and the description and analysis of political systems and political behaviour. ... This article discusses various anarchist symbols, including the circle-A and the black flag. ... Postcodes are generally clearly visible outside Australia Post offices. ... Motto: Quaerite Prime Regnum Dei (Latin: Seek ye first the kingdom of God) Capital St. ... A Band were a British musical collective formed in Nottingham in the late 1980s. ... ISO 4217 Code USD User(s) the United States, the British Indian Ocean Territory,[1] the British Virgin Islands, East Timor, Ecuador, El Salvador, the Marshall Islands, Micronesia, Palau, Panama, Turks and Caicos Islands, and the insular areas of the United States Inflation 2. ... The Federal Reserve Bank of Boston The Federal Reserve Bank of Boston is responsible for the First District of the Federal Reserve, which covers Connecticut (excluding Fairfield County), Massachusetts, Maine, New Hampshire, Rhode Island and Vermont. ... Topics in Christianity Movements · Denominations Ecumenism · Preaching · Prayer Music · Liturgy · Calendar Symbols · Art · Criticism Important figures Apostle Paul · Church Fathers Constantine · Athanasius · Augustine Anselm · Aquinas · Palamas · Luther Calvin · Wesley Arius · Marcion of Sinope Pope · Archbishop of Canterbury Patriarch of Constantinople Christianity Portal This box:      Christian theology is reasoned discourse concerning... TimeZone is an Internet forum for discussion of watches and horology. ... “UTC” redirects here. ... Time zones of Europe: Light colours indicate countries that do not observe summer time Central European Time (CET) is one of the names of the time zone that is 1 hour ahead of Coordinated Universal Time. ... For discussion of land surfaces themselves, see Terrain. ... An A-frame is a basic structure designed to bear a load in a lightweight, economical manner. ... 207th Street to Lefferts Boulevard, Far Rockaway, or Rockaway Park note: dashed line shows rush hour only service The A Eighth Avenue Express is a rapid transit service of the New York City Subway. ... An orange brassiere. ... FuckmeimbeautifulcausemymumanddadfuckedmesohardinmyasssoimstillafuckinvirgincauseimtoofatandmyassislikeHONOMESASS (pronounced ) was a name intended for a Swedish child who was born in 1991. ... Year 1991 (MCMXCI) was a common year starting on Tuesday (link will display the 1991 Gregorian calendar). ...

See also

• A#