Proto-Indo-European root meaning "to cover, conceal, save."

It forms all or part of: Anselm; apocalypse; Brussels; caliology; Calypso; calyx; ceiling; cell; cellar; cellular; cellulite; cellulitis; cilia; clandestine; cojones; coleoptera; color; conceal; eucalyptus; hall; hell; helm (n.2) "a helmet;" helmet; hold (n.2) "space in a ship below the lower deck;" hole; hollow; holster; housing (n.2) "ornamental covering;" hull (n.1) "seed covering;" kil-; kleptomania; occult; rathskeller; supercilious; Valhalla; William.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit cala "hut, house, hall;" Greek kalia "hut, nest," kalyptein "to cover," koleon, koleos "sheath," kelyphos "shell, husk;" Latin cella "small room, store room, hut," celare "to hide, conceal," clam "secret," clepere "to steal, listen secretly to;" Old Irish cuile "cellar," celim "hide," Middle Irish cul "defense, shelter;" Gothic hulistr "covering," Old English heolstor "lurking-hole, cave, covering," Gothic huljan "to cover over," hulundi "hole," hilms "helmet," halja "hell," Old English hol "cave," holu "husk, pod;" Old Prussian au-klipts "hidden;" Old Church Slavonic poklopu "cover, wrapping."

medieval weapon (a broad blade with sharp edges, ending in a point and mounted on a long handle), late 15c., from French hallebarde (earlier alabarde, 15c.), from Middle High German halmbarte "broad-axe with handle," from halm "handle" (see helm) + barte "hatchet," from Proto-Germanic *bardoz "beard" (see beard (n.)), also "hatchet, broadax" ("because the actual axe looks like a beard stuck to the wooden handle" - Boutkan). An alternative etymology [Kluge, Darmesteter] traces first element to helm "helmet," making the weapon an axe for smashing helmets. In 15c.-16c. especially the arm of foot-soldiers.

mid-15c., perhaps a diminutive of Middle English helm (see helm (n.2)). But some sources suggest Old French heaumet (Modern French heaume), a French diminutive of helme "helmet," from the same Germanic source as helm (n.2); Barnhart writes: "Old English helm never became an active term in the standard vocabulary of English."

masc. proper name, from Old North French Willaume, Norman form of French Guillaume, of Germanic origin (cognates: Old High German Willahelm, German Wilhelm), from willio "will" (see will (n.)) + helma "helmet," from Proto-Germanic *helmaz "protective covering" (from PIE root *kel- (1) "to cover, conceal, save;" compare helm (n.2)). After the Conquest, the most popular given name in England until supplanted by John.