ceruleum

From Latin ceruleum (“dark blue, dark green”).

ceruleum (uncountable)

1. A greenish-blue pigment consisting essentially of cobalt stannate.

• cerulean

ceruleum

1. inflection of ceruleus:
   1. nominative/accusative/vocative neuter singular
   2. accusative masculine singular

• "ceruleum", in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)