from
The Collaborative International Dictionary of English v.0.48
Solarium \So*la"ri*um\, 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]