The opposite force to gravity is often referred to as ‘normal force.’
Gravity is the force that pulls objects toward the center of the Earth (or any other massive body). When an object is resting on a surface, that surface exerts an upward force against the object. This is the normal force. It acts perpendicular to the surface and counteracts the force of gravity, keeping the object from accelerating downwards.
For example, if you place a book on a table, gravity pulls the book down with a certain force. In response, the table exerts a normal force upwards, equal in magnitude to the gravitational force (assuming the table is not bending or breaking). This balance of forces allows the book to remain at rest on the table. Without the normal force, the book would fall due to gravity.