Is it ensure, insure, or assure?
c.1400, "to die," from Middle French expirer (12c.) "expire, elapse," from Latin expirare/exspirare "breathe out, breathe one's last, die," from ex- "out" (see ex-) + spirare "to breathe" (see spirit). "Die" is the older sense in English; that of "breathe out" is first attested 1580s. Of laws, patents, treaties, etc., mid-15c. Related: Expired; expiring.
expire ex·pire (ĭk-spīr')
v. ex·pired, ex·pir·ing, ex·pires
To breathe one's last breath; die.