(business, US) A retailer that offers a wider selection of merchandise in a category than existing retailers, at lower prices, thereby gaining substantial share of the market and "killing" the existing retailers.

(mathematics) A branch of mathematics which deals with spaces and maps between them in abstraction, taking similar theorems from various disparate more concrete branches of mathematics and unifying them.

(linguistics) A linguistic category of words (or more precisely lexical items), generally defined by the syntactic or morphological behaviour of the lexical item in question, such as noun or verb.

A semantic or ontological error by which a property is ascribed to a thing that could not possibly have that property.

(category theory) A category 𝒞 with a bifunctor ⊗:𝒞⨯𝒞→𝒞 which may be called tensor product, an associativity isomorphism 𝛼_(A,B,C):(A⊗B)⊗C≃A⊗(B⊗C), an object I which may be called tensor unit, a left unit natural isomorphism 𝜆_A:I⊗A≃A, a right unit natural isomorphism 𝜌_A:A⊗I≃A, and some "coherence conditions" (pentagon and triangle commutative diagrams for those isomorphisms).

(category theory) A category naturally associated to any monad T, and equivalent to the category of free T-algebras.

(information science) A reference that specifies within some taxonomy or text typology one or more defined categories into which the referenced article, computer file etc. belongs.

plural of category reference

plural of category mistake

(linguistics) A type of formal grammar of natural language syntax.