hegemonist n.

1560s, "preponderance, dominance, leadership," originally of predominance of one city state or another in Greek history; from Greek hēgemonia "leadership, a leading the way, a going first;" also "the authority or sovereignty of one city-state over a number of others," as Athens in Attica, Thebes in Boeotia; from hēgemon "leader, an authority, commander, sovereign," from hēgeisthai "to lead," perhaps originally "to track down," from PIE *sag-eyo-, from root *sag- "to seek out, track down, trace" (see seek). In reference to modern situations from 1850, at first of Prussia in relation to other German states.

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.