A group, often named or numbered, to which items are assigned based on similarity or defined criteria.

plural of category

categorical, absolute, without exception / categorical, pertaining to a category / pertaining to categorial grammar

In a categorial manner.

(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.

Alternative spelling of subcategory

plural of sub-category (alternative spelling of subcategories).

plural of category killer

(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.

(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.