Is it ensure, insure, or assure?
c.1600, from Middle French desgouster "have a distaste for" (see disgust (n.)). Sense has strengthened over time, and subject and object have been reversed: cf. "It is not very palatable, which makes some disgust it" (1660s). The reverse sense of "to excite nausea" is attested from 1640s. Related: Disgusted; disgusting.