separatist

early 15c., separaten, transitive, "remove, detach completely; divide (something), sever the connection or association of," from Latin separatus, past participle of separare "to pull apart," from se- "apart" (see secret (n.)) + parare "make ready, prepare" (from PIE root *pere- (1) "to produce, procure"). Sever (q.v.) is a doublet, via French. Intransitive sense of "to part, be or become disunited or disconnected" is by 1630s of things, 1680s of persons. Related: Separated; separating.

word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.

Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.