Bulging out is a phrase used to describe something that is protruding or jutting out. Antonyms are words that have the opposite meaning of a given word. Therefore, antonyms for bulging out could include words such as sinking, contracting, withdrawing or receding. These words describe a decrease or a decrease in size rather than an increase in size or protrusion. Other antonyms for bulging out might include terms like flattening, compressing, or deflating, all of which describe the opposite of something that is bulging out. Antonyms serve as useful tools in expanding one's vocabulary and sharpening one's understanding of language.