Dictionary > English Dictionary > Definition, synonym and antonym of category
Meaning of category by Wiktionary Dictionary



    From Middle French categorie, from Late Latin categoria ( “class of predicables” ), from Ancient Greek κατηγορία ( kategoria, “head of predicables” ) .


    • IPA: /ˈkætəˌɡoɹi/


    category ( plural: categories )

    1. A group, often named or numbered, to which items are assigned based on similarity or defined criteria .
      This steep and dangerous climb belongs to the most difficult category .
      I wouldn't put this book in the same category as the author's first novel .
    2. ( mathematics ) A collection of objects, together with a transitively closed collection of composable arrows between them, such that every object has an identity arrow, and such that arrow composition is associative .
      One well-known category has sets as objects and functions as arrows .
      Just as a monoid consists of an underlying set with a binary operation "on top of it" which is closed, associative and with an identity, a category consists of an underlying digraph with an arrow composition operation "on top of it" which is transitively closed, associative, and with an identity at each object. In fact, a category's composition operation, when restricted to a single one of its objects, turns that object's set of arrows ( which would all be loops ) into a monoid .


    • ( group to which items are assigned ): class, family, genus, group, kingdom, order, phylum, race, tribe, type
    • See also Wikisaurus:class

    External links

    • category in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913
    • category in The Century Dictionary, The Century Co., New York, 1911

Explanation of category by Wordnet Dictionary


    1. a general concept that marks divisions or coordinations in a conceptual scheme

    2. a collection of things sharing a common attribute