A sore loser is a person who cannot accept defeat gracefully and behaves poorly when they lose. When we use this term, it often indicates that a person is acting childish or immature. Some synonyms to describe the behavior of a sore loser include bad sport, poor loser, crybaby, whiner, sulker, complainer, defeatist, grumbler, and spoilsport. These words all carry a negative connotation and are used to describe someone who does not handle failure well. While it can be difficult to lose, it's important to remember that it's a part of life, and we need to learn to handle defeat just as gracefully as we accept victory.