(phylogenetics) A paraphyletic group consisting of an ancestor and all its descendants, excluding the living representatives of a collection of species.

(US, law) Any of the functionally equivalent chemical entities referenced in a Markush claim.

The behaviour of a group of people governed by their mutual interaction. / The study of this behaviour.

(business) The practice of purchasing products and services at reduced prices on the condition that a minimum number of buyers would make the purchase.

(group theory) Any group of invertible matrices over a specified field, with the group operation of matrix multiplication.

(group theory) Any group that is isomorphic to a matrix group.

(group theory) For given n, the group of n×n unitary matrices, with the group operation of matrix multiplication.

(Internet) A group of people who meet and chat online, especially in a chat room

(group theory) For given n and field F (especially where F is the real numbers), the group of n × n orthogonal matrices with elements in F, where the group operation is matrix multiplication.

plural of family grouping