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."
"exile by ostracism, banish by popular vote," also in a figurative sense, "to exclude from society or favor," 1640s, from Latinized form of Greek ostrakizein "to banish," literally "to banish by voting with potshards" (see ostracism). Related: Ostracization; ostracized; ostracizing.
early 15c., "to shut out, exclude" (from a place), also "prevent, prohibit" (an action), from French débarrer, from Old French desbarer (12c., which, however, meant only "to unbar, unbolt," from des- "do the opposite of" (see dis-) + barrer "to bar," from barre "bar" (see bar (n.1)). The meaning turned around in French as the de- was felt in a different sense, perhaps as an intensifier. Related: Debarment; debarred.