Is it ensure, insure, or assure?
1540s, from Late Latin siccativus "drying, siccative," from Latin siccatus, past participle of siccare "to dry, make dry; dry up," from siccus "dry, thirsty; without rain," from PIE root *seikw- "to flow out" (cf. Avestan hiku- "dry," Greek iskhnos "dry, withered," Lithuanian seklus "shallow," Middle Irish sesc "dry," Sanskrit sincati "makes dry"). The noun is first recorded 1825.
siccative sic·ca·tive (sĭk'ə-tĭv)
A substance added to some medicines to promote drying; a drier.