A rebid by opener in a lower ranking new suit at the three level after a two- over-one response, eg 1♠-Pass-2♥– Pass-3♦. It is normal to play this bid as forcing to game. You need at least five cards in your first suit, at least four cards in your second and better than a minimum opening. Your second suit may be shorter than your first suit or the same length. For the sequence quoted, either of these hands would be fine:
