"Peter out" is a common phrase used to describe something that is gradually decreasing, losing momentum or coming to an end. The antonyms of this phrase include words that indicate an increase, acceleration, or continuation of something. These words are "strengthen," "intensify," "flourish," "thrive," and "prosper." When these words are used in a sentence, they convey a sense of growth or progress. For instance, "the business is flourishing," "the team's performance is intensifying," or "the economy is prospering." These antonyms for "peter out" are relevant in various contexts such as business, sports, and daily life situations, where growth and progress are important.