-ist


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.
Compare -ism, -istic, -ize.

Origin of -ist

Middle English -iste < Latin -ista < Greek -istēs; in some words, representing French -iste, German -ist, Italian -ista, etc., ≪ Latin < Greek, as above
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British Dictionary definitions for -ist

-ist


suffix

(forming nouns) a person who performs a certain action or is concerned with something specifiedmotorist; soloist
(forming nouns) a person who practises in a specific fieldphysicist; typist
(forming nouns and adjectives) a person who advocates a particular doctrine, system, etc, or relating to such a person or the doctrine advocatedsocialist
(forming nouns and adjectives) a person characterized by a specified trait, tendency, etc, or relating to such a person or traitpurist
(forming nouns and adjectives) a person who is prejudiced on the basis specifiedsexist; ageist

Word Origin for -ist

via Old French from Latin -ista, -istēs, from Greek -istēs
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012