Elastic collision means COLLISION AND REBOUND WITHOUT LOSS OF ENERGY.
There are two basic types of collision, they are elastic and inelastic collision. Elastic collision is said to occur when when two bodies collide in such a way that the kinetic energy of the bodies before collision is the same as their kinetic energy after collision, that is, no energy is lost and momentum also is conserved. In inelastic collision, kinetic energy is always lost.
