what is the planetary
â¢ PLANETARY (adjective). The adjective PLANETARY has 4 senses: 1. of or relating to or resembling the physical or orbital characteristics of a planet or the planets. 2. of or relating to or characteristic of the planet Earth or its inhabitants. 3. having no fixed course. 4. involving the entire earth; not limited or provincial in scope. Familiarity information: PLANETARY used as an adjective is uncommon.