Definition from Wiktionary, the free dictionary
- (grammar) A word preceding a noun to indicate that the noun refers to any member of the class of objects named by the noun.
Usage notes 
- In English, this term can be represented as a (before a consonant sound) or an (before a vowel sound) in the singular; in the plural, an article isn't used at all, or the pronoun some is used instead.
word preceding a noun to indicate any member of the class of objects