planetary

adjective

1. of, relating to, or resembling a planet or the planets.
2. wandering; erratic.
3. terrestrial; global.
4. Machinery. noting or pertaining to an epicyclic gear train in which a sun gear is linked to one or more planet gears also engaging with an encircling ring gear.

noun

5. Machinery. a planetary gear train.

adjective

1. of or relating to a planet
2. mundane; terrestrial
3. wandering or erratic
4. astrology under the influence of one of the planets
5. (of a gear, esp an epicyclic gear) having an axis that rotates around that of another gear
6. (of an electron) having an orbit around the nucleus of an atom

noun plural -taries

7. a train of planetary gears

adj.1590s; see planet + -ary. Probably from Late Latin planetarius “pertaining to a planet or planets,” but this is attested only as “an astrologer.” Planetary nebula, so called for its shape, attested from 1785.

1. In the traditional model of solar systems, a celestial body larger than an asteroid or comet, illuminated by light from a star, such as the Sun, around which it revolves.
2. A celestial body that orbits the Sun, has sufficient mass to assume nearly a round shape, clears out dust and debris from the neighborhood around its orbit, and is not a satellite of another planet. The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was considered to be a planet until its reclassification in 2006 as a dwarf planet. A planetlike body with more than about ten times the mass of Jupiter would be considered a brown dwarf rather than a planet. See also extrasolar planet inner planet outer planet.