pen·e·tra·lia \ˌpenə.ˈtrālēə\noun plural Etymology: Latin, plural of penetrale 1.: the innermost or most private parts of some thing or place (as a temple or palace) < explored the shuddery penetralia of caves — Spencer Brown > 2.: hidden things or secrets : privacy, sanctuary < admitted to the inmost penetralia of affairs — A.C.Benson >