early 15c., "carnal, unspiritual;" mid-15c., "of or pertaining to the senses," from Old French sensuel (15c.) and directly from Late Latin sensualis "endowed with feeling" (see sensuality). Meaning "connected with gratification of the senses," especially "lewd, unchaste" is attested from late 15c.
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.