*solarium*

‖n.; pl. Solaria [ L. See Solar, n. ] 1. An apartment freely exposed to the sun; anciently, an apartment or inclosure on the roof of a house; in modern times, an apartment in a hospital, used as a resort for convalescents. [ 1913 Webster ]

2. (Zool.) Any one of several species of handsome marine spiral shells of the genus Solarium and allied genera. The shell is conical, and usually has a large, deep umbilicus exposing the upper whorls. Called also perspective shell. [ 1913 Webster ]