In linguistics, a grammatical word belongs to one of the "closed" parts of speech such as pronouns, numerals, and prepositions, which do not readily admit new members. We have only to consider the failure of proposals for a gender neutral pronoun for English, to see how difficult it is to create a new pronoun that is actually adopted by speakers of a language. In linguistics and grammar, a pronoun is a pro-form that substitutes a noun or noun phrase with or without a determiner, such as you and they in English. ... A numeral is a symbol or group of symbols that represents a number. ... In grammar, a preposition is a type of adposition, a grammatical particle that establishes a relationship between an object (usually a noun phrase) and some other part of the sentence, often expressing a location in place or time. ... In non-sexist language, gender-neutral or epicene pronouns neither reveal nor imply sex or gender when referring to people, animals or things. ...

This contrasts with lexical words, which belong to the "open" parts of speech, such as nouns, verbs, and adjectives. People coin new lexical words all the time; a popular song or presidential speech is all it takes to add a new lexical word to the language. That is, these parts of speech are "open" to new additions. A noun, or noun substantive, is a word or phrase that refers to a person, place, thing, event, substance or quality. ... A verb is a part of speech that usually denotes action (bring, read), occurrence (to decompose (itself), to glitter), or a state of being (exist, live, soak, stand). Depending on the language, a verb may vary in form according to many factors, possibly including its tense, aspect, mood and voice. ... An adjective is a part of speech which modifies a noun, usually making its meaning more specific. ... Words and phrases are often created, or coined, by combining existing words, or by giving words new and unique suffixes and/or prefixes. ...

Lexical and grammatical words often behave differently. Often grammatical words to not make full use of all the sounds in a language. For example, in some of the Khoisan languages, most lexical words begin with clicks, but very few grammatical words do. In Mandarin Chinese, many grammatical words lack tone, but every lexical word has a tone. Map showing the distribution of the Khoi-San languages. ... Clicks are stops produced with two articulatory closures in the oral cavity. ... This article is on all of the Northern Chinese dialects. ... This article or section uses Ruby annotation. ...