key

{{11}}key (n.¹) "metal piece that works a lock," from O.E. cæg "key," of unknown origin, with no certain cognates other than O.Fris. kei. Perhaps related to M.L.G. keie "lance, spear" on notion of "tool to cleave with," from P.Gmc. *ki- "to cleaver, split" (Cf. Ger. Keil "wedge," Goth. us-kijans "come forth," said of seed sprouts, keinan "to germinate"). But Liberman writes, "The original meaning of *kaig-jo- was presumably '*pin with a twisted end.' Words with the root *kai- followed by a consonant meaning 'crooked, bent; twisted' are common only in the North Germanic languages." Modern pronunciation is a northern variant predominating from c.1700; earlier it was often spelled and pronounced kay.

Figurative sense of "that which serves to open or explain" was in O.E.; meaning "that which holds together other parts" is from 1520s. As "answer to a test," it is from chess, short for key move, "first move in a solution to a set problem." Musical sense of "tone, note" is 15c., but modern sense of "scale" is 1580s, probably as a translation of L. clavis or Fr. clef (see CLEF (Cf. clef); also Cf. KEYNOTE (Cf. keynote)). Extended c.1500 to "mechanism on a musical instrument." As a verb meaning "to scratch (a car's paint job) with a key" it is recorded by 1986.

{{12}}key (n.²) "low island," 1690s, from Sp. cayo "shoal, reef," from Taino cayo "small island;" spelling influenced by M.E. key "wharf" (c.1300), from O.Fr. kai "sand bank" (see QUAY (Cf. quay)).