caliology (n.)

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."

word-forming element indicating "branch of knowledge, science," now the usual form of -logy. Originally used c. 1800 in nonce formations (commonsensology, etc.), it gained legitimacy by influence of the proper formation in geology, mythology, etc., where the -o- is a stem vowel in the previous element.

The second element is prop[erly] -logy (-logue, etc.), the -o- belonging to the preceding element; but the accent makes the apparent element in E[nglish] to be -ology, which is hence often used as an independent word. [Century Dictionary]