hates losing; competitive; sore loser
Describes a person who strongly dislikes losing and will go to great lengths to win or avoid admitting defeat. Can be used positively (determined, competitive) or negatively (stubborn, ungracious).
He hates losing, so he seriously tries to win any game.
Her competitive nature helped her grow.
My little brother hates to lose, and he gets angry as soon as he loses at a game.
She has a competitive personality and always wants to be number one at everything.