About replay attack definition I have read .
Replay attack is a kind of attack in that the attacker eavesdrops valid message and sends that message repeatedly to make requestor in busy mode. It can be prevented by adding timestamp to the broadcasted message.

Does that definition true? Some says that the definition seems to be incorrect.
Replay attack is a form of network attack in which the attacker records messages and replays them later. Generally attacker uses them to get authenticated during one way or two way authentication. 
Random nonces are used to prevent them instead of timestamp as the latter requires clock synchronization which is tough in practice.