Is it ensure, insure, or assure?
1560s, from Latin fascia "a band, bandage, swathe" (see fasces). Originally in architecture; anatomical use is from 1788.
fascia fas·ci·a (fāsh'ē-ə)n. pl. fas·ci·ae (fāsh'ē-ē', fā'shē-ē) A sheet or band of fibrous connective tissue enveloping, separating, or binding together muscles, organs, and other soft structures of the body.