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]

c. 1400, "to put a cap on," from cap (n.); the meaning "cover as with a cap" is from c. 1600. The figurative sense of "complete, consummate, bring to a climax" is from 1580s; that of "go one better, outdo, excel" is by 1821. Related: Capped; capping. To cap verses (1610s) was "to quote alternately verses each beginning with the same letter with which the last ended."

The capping of Latin verses is a common game in classical schools. No verse may be used twice, and no hesitation or delay is permitted; so that a moderate proficiency in the game supposes several thousand verses arranged in the memory alphabetically. [Century Dictionary, 1895]

late Old English cæppe "hood, head-covering, cape," a general Germanic borrowing (compare Old Frisian and Middle Dutch kappe, Old High German chappa) from Late Latin cappa "a cape, hooded cloak" (source of Spanish capa, Old North French cape, French chape), a word of uncertain origin. Possibly a shortened from capitulare "headdress," from Latin caput "head" (from PIE root *kaput- "head").

The Late Latin word apparently originally meant "a woman's head-covering," but the sense was transferred to "hood of a cloak," then to "cloak" itself, though the various senses co-existed. Old English took in two forms of the Late Latin word, one meaning "head-covering," the other "ecclesiastical dress" (see cape (n.1)). In most Romance languages, a diminutive of Late Latin cappa has become the usual word for "head-covering" (such as French chapeau).

The meaning "soft, small, close-fitted head covering" in English is from early 13c., originally for women; extended to men late 14c.; extended to cap-like coverings on the ends of anything (as in hubcap) from mid-15c. The meaning "contraceptive device" is by 1916.

The meaning "cap-shaped piece of copper lined with gunpowder and used to ignite a firearm" is by 1825, hence cap-gun (1855); extended to paper strips used in toy pistols by 1872 (cap-pistol is from 1879).

Figurative thinking cap is from 1839 (considering cap is 1650s). Cap and bells (1781) was the insignia of a fool; cap and gown (1732) of a scholar. To set one's cap at or for (1773) means "use measures to gain the regard or affection of," usually in reference to a woman seeking a man's courtship.

a type of woman's indoor cap with a bag-shaped crown and a broad band and frills, 1795 (as simply mob, 1748), from cap (n.) + obsolete mob (n.) "negligent attire" (1660s), earlier "a strumpet" (earlier form mab, 1550s), which is related to the obsolete verb mob "to tousle the hair, to dress untidily" (1660s), and perhaps is ultimately from mop (n.), but has been influenced by Mab as a female name. Dutch has a similar compound, mopmuts, but the relationship between it and the English word is uncertain.

"a general or continuous permanent covering of a certain area of land, whether large or small, with snow or ice, especially in the arctic regions," 1859 in geology, from ice (n.) + an extended sense of cap (n.).

"all over" (in reference to dress or armor), 1520s, from French cap-à-pie, literally "head to foot." The more usual French form is de pied en cap. The French words are from Latin caput "head" (from PIE root *kaput- "head") + pedem "foot" (from PIE root *ped- "foot").

also skullcap, "cap fitting closely to the head," 1680s, from skull (n.) + cap (n.).

"player of a percussion instrument," 1921, from percussion + -ist. Earlier "one who uses a percussion gun" (1817).

"of or pertaining to percussion," 1735, from Latin percuss-, past-participle stem of percutere "to strike hard" (see percussion) + -ive. It was used earlier as a noun, "a repercussive medicine" (late 14c.).

gourd rattle used as a Latin-American percussion instrument, 1813, from Portuguese, from a Brazilian native name. Related: Maracas.