Is it ensure, insure, or assure?
late 14c., "mental derangement characterized by excitement and delusion," from Late Latin mania "insanity, madness," from Greek mania "madness, frenzy; enthusiasm, inspired frenzy; mad passion, fury," related to mainesthai "to rage, go mad," mantis "seer," menos "passion, spirit," all from PIE *men- "to think, to have one's mind aroused, rage, be furious" (see mind (n.)). Sense of "fad, craze" is 1680s, from French manie in this sense. Sometimes nativized in Middle English as manye. Used since 1500s (in imitation of Greek) as the second element in compounds expressing particular types of madness (cf. nymphomania, 1775; kleptomania, 1830; megalomania, 1890).
mania ma·ni·a (mā'nē-ə, mān'yə)
A manifestation of bipolar disorder characterized by profuse and rapidly changing ideas, exaggerated gaiety, and excessive physical activity.
An abnormal compulsion or an extreme love for: pyromania.
Violent, abnormal, or impulsive behavior. In psychological terms, mania is wild activity associated with manic depression.
Note: A “mania” in popular terms is an intense enthusiasm or craze.
in psychiatric terminology, any abnormal or unusual state of excitement, as in the manic phase of bipolar disorder.