Gravitation \Grav"i*ta"tion\, n. [Cf. F. gravitation. See Gravity.]

1. The act of gravitating.

2. (Pysics) 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.

Law of gravitation, that law in accordance with which gravitation acts, namely, that every two bodies or portions of matter in the universe attract each other with a force proportional directly to the quantity of matter they contain, and inversely to the squares of their distances.

Source: Webster's Revised Unabridged Dictionary (1913)