Found 2 items, similar to Planetary nebula.
English → English (WordNet) Definition: planetary nebula planetary nebula n : a nebula that was once thought to be a star with its planets but is now thought to be a very hot star surrounded by an expanding envelope of ionized gases that emit a fluorescent glow because of intense radiation from the star
English → English (gcide) Definition: Planetary nebula Planetary \Plan"et*a*ry\, a. [Cf. L. planetarius an astrologer, F. plan['e]taire planetary. See Planet.] 1. Of or pertaining to the planets; as, planetary inhabitants; planetary motions; planetary year. [1913 Webster] 2. Consisting of planets; as, a planetary system. [1913 Webster] 3. (Astrol.) Under the dominion or influence of a planet. “Skilled in the planetary hours.” --Drayton. [1913 Webster] 4. Caused by planets. “A planetary plague.” --Shak. [1913 Webster] 5. Having the nature of a planet; erratic; revolving; wandering. “Erratical and planetary life.” --Fuller. [1913 Webster] Planetary days, the days of the week as shared among the planets known to the ancients, each having its day. --Hutton. Planetary nebula, a nebula exhibiting a uniform disk, like that of a planet. [1913 Webster]