Definition: An article that makes a noun refer to a nonspecific item (or items) of its class. The indefinite articles are "a" and "an" in English and un, una, unos and unas in Spanish. The word "some" can be classified as an indefinite in English when it is used in a way similar to unos and unas.

Note that Spanish and English have different grammatical rules concerning when indefinite articles are needed or should be omitted.

Also known as: Artículo indefinido in Spanish.

Examples: Boldfaced words are indefinite articles:

• He bought a house. (Compró una casa.)
• She is reading some books. (Lee unos libros.)
• I am a teacher. (Soy profesor.)