Antonyms are words that have opposite meanings to each other. The phrase "buys back" means to purchase something that has been sold or given away previously. Therefore, its antonyms would include words such as "sells off," "disposes of," or "relinquishes." These terms mean to give up or sell something, rather than retain or acquire it. Other opposites to "buys back" could include words like "abdicates," "surrenders," and "renounces," which carry meanings of relinquishing or refusing something that was once given away or held. These antonyms can help to enrich our vocabulary and express opposing ideas, providing a range of options for us to choose from in our communication.