In linguistics, grammatical number is a grammatical category of nouns, pronouns, and adjective and verb agreement that expresses count distinctions (such as "one", "two", or "three or more").

The count distinctions typically, but not always, correspond to the actual count of the referents of the marked noun or pronoun.

The word "number" is also used in linguistics to describe the distinction between certain grammatical aspects that indicate the number of times an event occurs, such as the semelfactive aspect, the iterative aspect, etc. For that use of the term, see "Grammatical aspect".

Most languages of the world have formal means to express differences of number. One widespread distinction, found in English and many other languages, involves a simple two-way number contrast between singular and plural (car/cars, child/children, etc.). Discussion of other more elaborate systems of number appears below.

Grammatical number is a morphological category characterized by the expression of quantity through inflection or agreement. As an example, consider the English sentences below:

Avram Noam Chomsky (/ˈnoʊm ˈtʃɒmski/; born December 7, 1928) is an American linguist, philosopher,cognitive scientist, historian, and activist. He is an Institute Professor and Professor (Emeritus) in the Department of Linguistics & Philosophy at MIT, where he has worked for over 50 years. Chomsky has been described as the "father of modern linguistics" and a major figure of analytic philosophy. His work has influenced fields such as computer science, mathematics, and psychology.

Ideologically identifying with anarcho-syndicalism and libertarian socialism, Chomsky is known for his critiques of U.S. foreign policy and contemporary capitalism, and he has been described as a prominent cultural figure. His media criticism has included Manufacturing Consent: The Political Economy of the Mass Media (1988), co-written with Edward S. Herman, an analysis articulating the propaganda model theory for examining the media.

According to the Arts and Humanities Citation Index in 1992, Chomsky was cited as a source more often than any other living scholar from 1980 to 1992, and was the eighth most cited source overall. Chomsky is the author of over 100 books. He is credited as the creator or co-creator of the Chomsky hierarchy, the universal grammar theory, and the Chomsky–Schützenberger theorem.