Is it ensure, insure, or assure?
mid-15c., from Middle French pensée "a pansy," literally "thought, remembrance," from fem. past participle of penser "to think," from Latin pensare "consider," frequentative of pendere "to weigh" (see pensive). So called because it was regarded as a symbol of thought or remembrance. Meaning "effeminate homosexual man" is first recorded 1929.