A noun phrase (NP) in linguistics is a phrase based around a noun, functioning as a unit within a sentence. It typically includes the noun and its modifiers. For example, in the phrase “the big red ball,” “the big red ball” is a noun phrase, with “ball” as the head noun and “the,” “big,” and “red” as modifiers. Noun phrases can be simple, like “a cat,” or more complex, involving additional descriptors or clauses.