*ad-

c. 1300, abaten, "put an end to" (transitive); early 14c., "to grow less, diminish in power or influence" (intransitive); from Old French abatre "beat down, cast down, strike down; fell, destroy; abolish; reduce, lower" (Modern French abattre), from Vulgar Latin *abbatere, from Latin ad "to" (see ad-) + battuere "to beat" (see batter (v.)). The French literal sense of "to fell, slaughter" is in abatis and abattoir. Related: Abated; abating.

late 14c., "conflict, fighting; difficulty, trouble," a contraction of at do, literally "to do," a dialectal formation in the Norse-influenced areas of northern England: some Scandinavian languages used at with the infinitive of a verb where Modern English uses to.

From use of the infinitive in much ado ("much to do") and similar phrases, ado came to be regarded as a noun. Compare the sense evolution in to-do and affair (from French infinitive phrase à faire "to do"). The weakened meaning "fuss" is from early 15c. Also used in Middle English for "dealings, traffic," and "sexual intercourse" (both c. 1400).