Originally Boxing. Of a punch or blow: delivered with a swing of the arm, rather than with the arm thrust out from the shoulder in a straight…

Pugilism. Of a blow: Direct, full on the mark, ‘straight from the shoulder’.

Of a blow, etc.: that strikes on or from the side in the manner of a sidewinder (sidewinder, n.1); sideswiping. Also (and in earliest use) in…

of a blow, etc.: Such as to disable or knock out of the contest; also figurative.

Originally and chiefly U.S. Of a punch or blow: delivered with a wide swinging movement of the arm.

knock(ed) out (cf. kayo, v. n.).