"to reduce, to lessen in intensity," c.1300, aphetic of abate (q.v.). Now only in phrase bated breath, which was used by Shakespeare in "The Merchant of Venice" (1596).
c.1300, "to contend with blows or arguments," from O.Fr. batre "to hit, beat, strike," from L.L. battere, from L. batuere "to beat, knock" (see batter (v.)). In falconry, "to beat the wings impatiently and flutter away from the perch." Figurative sense of "to flutter downward" attested from 1580s.