heolstor, m/n.n: darkness, obscurity (also fig.); place of concealment, hiding-place, hidden recess. (HEH-ol-stor / ˈhɛɔl-stɔr)

Medieval manuscript image of an old man with a halo holding a globe in his hands, with one hemisphere black and the other white. Two bipedal human-faced lizard-like creatures creep in the margin above.
Les Histoires Roger. France, 13th century. Bibliothèque nationale de France, Département des Manuscrits, Français 20125, f. 2v. [gallica.bnf.fr]