1. to become afraid or lose confidence in doing something, especially at a critical moment
He was going to ask her to marry him, but he lost nerve at the last moment.
Ele ia pedir-lhe em casamento, mas perdeu a coragem no último momento.
2. to suddenly feel too scared or anxious to continue with a planned action
She lost nerve and didn't jump off the diving board.
Ela perdeu a coragem e não saltou do trampolim.