noun 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.
2. solarium ·noun 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.