Is it ensure, insure, or assure?
early 15c. (implied in adapted) "to fit (something, for some purpose)," from Middle French adapter (14c.), from Latin adaptare "adjust," from ad- "to" (see ad-) + aptare "join," from aptus "fitted" (see apt). Meaning "to undergo modification so as to fit new circumstances" (intransitive) is from 1956. Related: Adapting.