conceal v.

word-forming element meaning "together, with," sometimes merely intensive; it is the form of com- used in Latin before consonants except -b-, -p-, -l-, -m-, or -r-. In native English formations (such as costar), co- tends to be used where Latin would use con-.

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."

early 14c. (late 13c. in Anglo-French), "act of hiding or keeping secret," from Old French concelement "concealment, secrecy," from conceler "to hide" (see conceal). Originally a term in law, "intentional suppression of truth to the injury of another;" general sense of "state of being concealed" is from c. 1600.