Mass centers refer to the points in a body where the mass is considered to be concentrated. These points are crucial in calculations involving the body's motion and dynamics. Synonyms for mass centers include centroid, center of gravity, and balance point. The centroid is the geometric center of a body and is calculated by determining the average position of all the points in the body. The center of gravity is the point where the force of gravity can be considered to act, and it determines the stability and balance of the body. Finally, the balance point is the point where an object can be supported without tipping over. All these synonyms are indicative of the importance of mass centers in understanding an object's behavior.