The phrase "reining in" refers to controlling or restraining something or someone. Its antonyms are words that represent the opposite meaning of reining in. The opposite words of "reining in" are "encouraging," "motivating," and "stimulating." These words convey the idea of urging someone or something to move forward, progress, or improve. Other antonyms of reining in are "empowering," "liberating," and "freeing." They suggest unleashing or emboldening someone or something to act on their own accord or make their own choices. These antonyms give different shades of meaning to the absence of controlling or restraining influence on someone or something.