Is it ensure, insure, or assure?
late 12c., from Old French ermine (12c., Modern French hermine), both the animal and the fur, apparently from a convergence of Latin (mus) Armenius "Armenian (mouse)," ermines being abundant in Asia Minor; and an unrelated Germanic word for "weasel" (cf. Old High German harmo "ermine, stoat, weasel," adj. harmin; Old Saxon harmo, Old English hearma "shrew," etc.) that happened to sound like it.