Annum is a Latin noun meaning year. It is the accusative singular masculine of the second declension noun annus (nominative), anni (genitive) [1]. Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ...

• Per annum means "occurring every year".

• Kilo-annum, usually abbreviated as ka, is a unit of time equal to one thousand years.

• Mega-annum, usually abbreviated as Ma, is a unit of time equal to one million (10⁶) years. It is commonly used in scientific disciplines such as geology, paleontology, and celestial mechanics to signify very long time periods in the past. For example, the dinosaur species Tyrannosaurus rex flourished approximately 65 Ma (65 million years) ago (ago may not always be mentioned; if the quantity is specified while not explicitly discussing a duration, one can assume that "ago" is implied; "mya" includes "ago" explicitly.). In astronomical applications, the year used is the Julian year of precisely 365.25 days.

• Giga-annum, usually abbreviated as Ga, is a unit of time equal to one billion (10⁹) years. It is commonly used in scientific disciplines such as cosmology to signify extremely long time periods in the past. For example, the formation of the Earth occurred approximately 4.55 Ga (4.55 billion years) ago. As is clear from the notation, billion as used here is on the short scale.

A millennium is a period of time, equal to one thousand years (from Latin mille, thousand, and annum, year). ... For the techno single by Moby, see Thousand (single). ... A pocket watch. ... One million (1000000), one thousand thousand, is the natural number following 999999 and preceding 1000001. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history and the processes that shape it. ... A paleontologist carefully chips rock from a column of dinosaur vertebrae. ... Celestial mechanics is a division of astronomy dealing with the motions and gravitational effects of celestial objects. ... Orders & Suborders Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ... Binomial name Tyrannosaurus rex Osborn, 1905 Tyrannosaurus rex (ty-RAN-o-sawr-us) meaning king tyrant lizard because of its size and large teeth and claws (Greek tyrannos = tyrant + sauros = lizard; Latin rex = king), also known colloquially as T. rex and The King of the Dinosaurs, was a giant carnivorous... Mya has more than one meaning: Mya, an American R&B singer mya (unit), an abbreviation for million years ago, used as a unit of time in astronomy and geology mya, the ISO 639 alpha-3 code for the Burmese language General Bo Mya, Chief Commander of the Karen National... In astronomy, a Julian year is a unit of time defined as exactly 365. ... The word billion and its equivalents in other languages refer to either one million million or one thousand million, depending on whether the writer is using the long scale or the short scale. ... // Cosmology, from the Greek: κοσμολογία (cosmologia, κόσμος (cosmos) world + λογια (logia) discourse) is the study of the Universe in its totality, and by extension, humanitys place in it. ... Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ... // Short scale is the English translation of the French term échelle courte, which designates a system of numeric names in which the word billion means a thousand millions. ...

See also

• Before Present
• bya
• Geologic time scale
• Gya
• mya