Gravitation :: Gravitation (n.) That species of attraction or force by which all bodies or particles of matter in the universe tend toward each other; called also attraction of gravitation, universal gravitation, and universal gravity. See Attraction, and Weight..
Gravitational :: Gravitational (a.) Of or pertaining to the force of gravity; as, gravitational units..
Gravitative :: Gravitative (a.) Causing to gravitate; tending to a center.