Is it ensure, insure, or assure?
to banish or expel; abolish
Greek ostrakizein 'to banish by voting with potsherds'
1640s, from Greek ostrakizein "to banish," literally "to banish by voting with potshards" (see ostracism). Figurative sense of "to exclude from society" is attested from 1640s. Related: Ostracization; ostracized; ostracizing.