Is it ensure, insure, or assure?
"put an end to" (c.1300); "to grow less, diminish in power or influence" (early 14c.), from Old French abattre "beat down, cast down," from Vulgar Latin *abbatere, from Latin ad "to" (see ad-) + battuere "to beat" (see batter (v.)). Secondary sense of "to fell, slaughter" is in abatis and abattoir. Related: Abated; abating.