clavicle (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." 

common name of sister-queens in Egypt under the Ptolemaic Dynasty. The name is Latinized Greek, probably meaning "glory of her father," from kleos "rumor, report, news; good report, fame, glory" (from PIE root *kleu- "to hear") + patris, genitive of pater "father" (see father (n.)), though Shipley suggests "key to the fatherland," from kleis "key" (see clavicle). The famous queen was the seventh of that name. Related: Cleopatran.

medical Latin, from sterno- "sternum," Greek sternon "breast, breastbone," or Latin sternum (see sternum) + Latinized Greek kleis (see clavicle) + mastoid.