Be a bad loser is an expression used to describe someone who reacts negatively to losing. It is often seen as a negative trait, as it implies that the person is not able to accept defeat gracefully. The crossword solutions for this term are SULK (4 letters) and NOTACCEPTDEFEAT (15 letters). SULK means to show displeasure or ill humor by being silent or sullen. Notacceptdefeat means to refuse to accept defeat, which is the opposite of being a good sport.