gravitation
grav.i.ta.tion \.grav-*-'ta--sh*n\ \-shn*l, -sh*n-*l\ \-e-\ \'grav-*-.ta-t-iv\ n 1a: a force manifested by acceleration toward each other of two free materi al particles or bodies or of radiant-energy quanta 1b: the action or process of gravitating 2: an attraction to something - grav.i.ta.tion.al aj