A matchingcollection of similar things. (Note the similar meaning in Etymology 1, Noun.)
A collection of various objects for a particular purpose.
An object made up of several parts.
(set theory) A collection of zero or more objects, possibly infinite in size, and disregarding any order or repetition of the objects which may be contained within it.
(Britain, education) A class group in a subject where pupils are divided by ability.
(poker, slang)Three of a kind, especially if two cards are in one's hand and the third is a on the board. Compare trips (“three of a kind, especially with two cards on the board and one in one's hand”).
Verb
(Britain, education) To divide a class group in a subject according to ability