a suffix of nouns, often corresponding to verbs ending in -ize or nouns ending in -ism, that denote a person who practices or is concerned with something, or holds certain principles, doctrines, etc.: apologist; dramatist; machinist; novelist; realist; socialist; Thomist. Cf. -ism, -istic, -ize.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.