so·lar·i·um 
(sō-lârē-əm, sə-)
(sō-lârē-əm, sə-)n. pl. so·lar·i·a (-ē-ə) or so·lar·i·ums
A room, gallery, or glassed-in porch exposed to the sun.
[Latin sōlārium, terrace, flat housetop, from sōl, sun; see sāwel- in the Appendix of Indo-European roots.]