A specifically defined division in a system of classification; a class. A general class of ideas, terms, or things that mark divisions or coordinations within a conceptual scheme, especially: Aristotle's modes of objective being, such as quality, quantity, or relation, that are inherent in everything. Kant's modes of subjective understanding, such as singularity, universality, or particularity, that organize perceptions into knowledge. A basic logical type of philosophical conception in post-Kantian philosophy. Linguistics A classificatory structural unit or property of a language, such as a part of speech, verb phrase, or object. Linguistics A specific grammatical defining property of a linguistic unit or class, such as number or gender in the noun and tense or voice in the verb.