gravitation(fundamental force of attraction) noun [UK: ˌɡræ.vɪ.ˈteɪʃ.n̩] [US: ˌɡræ.və.ˈteɪʃ.n̩]
gravitational wave [gravitational waves](fluctuation in spacetime that propagates as a wave at the speed of light) noun [UK: ˌɡræ.vɪ.ˈteɪʃ.n̩əl weɪv] [US: ˌɡræ.və.ˈteɪʃ.n̩əl ˈweɪv]