planetary : Idioms & Phrases

• noun (astronomy) one of three empirical laws of planetary motion stated by Johannes Kepler
  Kepler's law.
  

WordNet

• the days of the week as shared among the planets known to the ancients, each having its day. Hutton.

Webster 1913

• noun an outer gear that revolves about a central sun gear of an epicyclic train
  planet gear; planet wheel; epicyclic gear.
  

WordNet

• noun (astrology) one of 12 equal areas into which the zodiac is divided
  house; star sign; sign of the zodiac; sign; mansion.
  

WordNet

• noun 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
  

WordNet

• a nebula exhibiting a uniform disk, like that of a planet.

Webster 1913