adj.1. Of, relating to, or resembling the physical or orbital characteristics of a planet or the planets.
2. a. Of or relating to the earth; terrestrial or earthly: measured the planetary tilt in degrees.
b. Of or affecting the entire world; global: a planetary consensus.
3. Wandering; erratic: a planetary life.
4. Being or relating to a gear train consisting of a central gear with an internal ring gear and one or more pinions.