early 15c., "carnal, concerning the body" (in distinction from the spirit or intellect);" mid-15c., "of, affecting, or pertaining to the (physical) senses" (a meaning now obsolete), from Old French sensual, sensuel (15c.) and directly from Late Latin sensualis "endowed with feeling" (see sensuality).
The specific meaning "connected with gratification of the senses" is from late 15c., especially "lewd, unchaste, devoted to voluptuous pleasures." Related: Sensually.
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.
<a href="https://www.etymonline.com/word/sensualist">Etymology of sensualist by etymonline</a>
Harper, D. (n.d.). Etymology of sensualist. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/sensualist