When we say someone "throws in the sponge," it means they give up or surrender. However, there are several words that are antonyms, or opposites, to this phrase. These words can be used to describe someone who perseveres, persists, or keeps fighting, even in the face of adversity. Some antonyms for "throws in the sponge" are: stays the course, soldiers on, never gives up, remains undaunted, persists, endures, and battles on. These words describe a person who is determined to see something through to the end, and who will not be defeated by setbacks or challenges.