tidal force

noun

1. the gravitational pull exerted by a celestial body that raises the tides on another body within the gravitational field, dependent on the varying distance between the bodies.

1. A secondary effect of the gravitational forces between two objects orbiting each other, such as the Earth and the Moon, that tends to elongate each body along the axis of a line connecting their centers. Tidal forces are responsible for the fluctuation of the tides as well as for the synchronous rotation of certain moons as they orbit their planets.