plan·e·tol·o·gy 
(plăn′ĭ-tŏlə-jē)
(plăn′ĭ-tŏlə-jē)n.
The branch of astronomy that deals with the composition and structure of the planets of the solar system and with the relationships, similarities, and differences between them.
plan′e·to·logi·cal (plăn′ĭ-tl-ŏjĭ-kəl) adj.
plan′e·tolo·gist n.
- graphically
- graphical user interface
- graphic arts
- graphic design
- graphic designer
- graphic equalizer
- graphicness
- graphic novel
- graphics
- graphics card
- graphics processor
- graphite
- graphitic
- graphitization
- graphitize
- graphological
- graphologist
- graphology
- graph paper
- -graphy
- grapiness
- grapnel
- grappa
- grapple
- grappler