1. of or relating to the sun: solar phenomena.
2. determined by the sun: solar hour.
3. proceeding from the sun, as light or heat.
4. operating by the light or heat of the sun, as a mechanism.
5. indicating time by means of or with reference to the sun: a solar chronometer.
6. Astrology subject to the influence of the sun.
7. any room, especially a large room or one on an upper storey, for family use in a large house or castle.
[L solaris ]
-- solarian, adjective