Is it ensure, insure, or assure?
1640s, "pertaining to the senses" apparently coined by Milton to recover the original meaning of sensual and avoid the lascivious connotation that the older word had acquired, but by 1870 sensuous, too, had begun down the same path and come to mean "alive to the pleasures of the senses." Rare before Coleridge popularized it "To express in one word all that appertains to the perception, considered as passive and merely recipient ...." (1814). From Latin sensus (see sense (n.)) + -ous. Related: Sensuously; sensuousness.