Is it ensure, insure, or assure?
Old English breowan "to brew" (class II strong verb, past tense breaw, past participle browen), from Proto-Germanic *breuwan "to brew" (cf. Old Norse brugga, Old Frisian briuwa, Middle Dutch brouwen, Old High German briuwan, German brauen "to brew"), from PIE root *bhreue- "to bubble, boil, effervesce" (cf. Sanskrit bhurnih "violent, passionate," Greek phrear "well, spring, cistern," Latin fervere "to boil, foam," Thracian Greek brytos "fermented liquor made from barley," Russian bruja "current," Old Irish bruth "heat;" Old English beorma "yeast;" Old High German brato "roast meat"), the original sense thus being "make a drink by boiling." Related: Brewed; brewing.
c.1500, "a brewed beverage," from brew (v.).
[first form 1940s+, third 1980s+; second form 1970s+ fr French brouhaha, ''fuss, ado'']