- 1[uncountable] the act or process of putting people or things into a group or class (= of classifying them) a style of music that defies classification (= is like no other)
- 2[countable] a group, class, division, etc. into which someone or something is put
- 3[uncountable] (biology) the act of putting animals, plants, etc. into groups, classes, or divisions according to their characteristics The classification of bony fish is extremely complicated.
- 4[countable] (technology) a system of arranging books, tapes, magazines, etc. in a library into groups according to their subject