The phrase "buoying up" is often used to describe the act of supporting someone or something, but there are many synonyms that can convey the same meaning. To encourage or lift someone's spirits, you can use words like "cheering," "inspiring," or "motivating." When supporting a team or cause, you can use "backing," "championing," or "advocating." To offer assistance or help during difficult times, you can use "aiding," "abetting," or "assisting." Whatever the situation, there are plenty of synonyms for "buoying up" that can convey the same supportive and positive message.