The phrase "petering out" is often used to describe something that gradually loses its intensity or effectiveness. To find antonyms for this phrase, we can look for words that describe the opposite: something that is gaining momentum and becoming more powerful. Some possible antonyms for "petering out" might include "building up," "growing stronger," or "intensifying." These words suggest a process or trend of growth and development, rather than a decline, and can help us frame our thoughts or actions in a more positive light. Whether we are working on a project, pursuing a goal, or navigating a relationship, it can be helpful to seek out positive and empowering language that encourages us to keep moving forward.