characterizing group

char·ac·ter·iz·ing group

a group of atoms in a molecule that distinguishes the class of substances in which it occurs from all other classes; thus, carbonyl (CO) is the characterizing group of ketones; COOH, of carboxylic acids, etc.

char·ac·ter·iz·ing group

(kar'ăk-tĕr-īz'ing grūp) A group of atoms in a molecule that distinguishes the class of substances in which it occurs from all other classes; thus carbonyl (CO) is the characterizing group of ketones; COOH, of organic acids, among other examples.