c. 1400, "act of beating or bruising; a bruise, an injury to the body without apparent wound or fracture," from Latin contusionem (nominative contusio) "a crushing, breaking, battering," in medical language, "a bruise," noun of action from past-participle stem of contundere "to beat, bruise, grind, crush, break to pieces," from assimilated form of com-, here perhaps an intensive prefix (see com-), + tundere "to beat" (see obtuse).
"contusion without laceration, superficial injury caused by impact," 1540s, from bruise (v.).
c. 1400, "a bruising, contusion (to the head)," from Latin concussionem (nominative concussio) "a shaking, an earthquake," noun of action from past-participle stem of concutere "shake violently," from assimilated form of com "with, together" (see con-) + quatere "to shake" (see quash).
From late 15c. as "act of shaking or agitation," especially by impact of another body; from 1540s as "brain injury caused by a fall or blow."
early 15c., percussioun, "a striking, a blow; internal injury, contusion," from Latin percussionem (nominative percussio) "a beating, striking; a beat as a measure of time," noun of action from past participle stem of percutere "to strike hard, beat, smite; strike through and through," from per "through" (from PIE root *per- (1) "forward," hence "through") + quatere "to strike, shake" (see quash).
In reference to musical instruments sounded by a stroke or blow, attested by 1776 (instrument of percussion). In medical diagnosis, "a method of striking or tapping the surface of the body to determine the condition of the organs in the region struck," by 1781.
The art of percussion, besides, although very simple in appearance, requires long practice, and a dexterity which few men can acquire. The slightest difference in the angle under which the fingers strike the thorax, may lead one to suspect a difference of sound which in reality does not exist. ["Laennec's New System of Diagnosis," in Quarterly Journal of Foreign Medicine and Surgery, November 1819]
