When it comes to finding synonyms for the word "mellowing," there are a variety of options to choose from. Some possibilities might include words like "softening," "relaxing," "calming," "soothing," "tempering," or "moderating." Other related terms that could be used depending on the context might include words like "toning down," "reducing," "cooling," "easing," or "pacifying." Whether you're describing the aging process of a fine wine or the gradual transformation of a person's personality over time, there are many different ways to capture the essence of "mellowing" using different words and phrases.