The description of the word you requested from the astronomical dictionary is given below.
Gravitation or the force of gravity acts between all things that have mass. Gravity is one of the four fundamental forces of nature, and is the most important one at astronomical scales (distances). Gravity is always an attracting force, and never repulsive. Thanks to gravity, we do not float away from Earth, the Earth stays together, and remains orbiting around the Sun. The Sun keeps shining partly because of gravity.