clavichord (n.)

also *kleu-, klēu-, Proto-Indo-European root meaning "hook, crook," also "crooked or forked branch" (used as a bar or bolt in primitive structures). 

It forms all or part of: anschluss; autoclave; clause;  claustrophobia; claves; clavichord; clavicle; clavier; claviger; clechy; clef; cloison; cloisonne; cloister; close (v.); close (adj.); closet; closure; cloture; clove (n.1) "dried flowerbud of a certain tropical tree, used as a spice;" cloy; conclave; conclude; disclose; enclave; enclose; exclude; foreclose; include; occlude; preclude; recluse; seclude; slot (n.2) "bar or bolt used to fasten a door, window, etc." 

It is the hypothetical source of/evidence for its existence is provided by: Greek kleis "bar, bolt, key; collarbone," klobos "cage;" Latin clavis "key," clavus "nail," claudere "to shut, close;" Lithuanian kliūti "to catch, be caught on," kliaudžiu, kliausti "to check, hinder," kliūvu, kliūti "to clasp, hang;" Old Church Slavonic ključi "hook, key," ključiti "shut;" Old Irish clo "nail," Middle Irish clithar "hedge, fence;" Old High German sliozan "shut," German schließen "to shut," Schlüssel "key." 

c. 1300, corde, "a string or small rope composed of several strands twisted or woven together; bowstring, hangman's rope," from Old French corde "rope, string, twist, cord," from Latin chorda "string of a musical instrument, cat-gut," from Greek khorde "string, catgut, chord, cord," from PIE root *ghere- "intestine."

Also from c. 1300 as "string of a musical instrument." From c. 1400 as "a tendon or muscle." Figurative sense of "anything which binds or restrains" is from late 14c. Meaning "raised, cord-like rib on the surface of cloth" is from 1776. As a measure of wood of 128 cubic feet (eight feet long, four feet high and wide) first recorded 1610s, so called because it was measured with a cord of rope.

1708, "keyboard of a pianoforte, organ, etc.," from French clavier, originally "a key-bearer," from Latin clavis "key" (from PIE root *klau- "hook"). The French word also is the source of German Klavier, Dutch klavier, Danish klaver, etc. The German word was used generally of keyboard instruments with strings, and is the source of the English use of the word for "a clavichord, a harpsichord, a pianoforte, an organ," attested from 1845.