Some synonyms for the word "double-hearted" are two-faced, insincere, duplicitous, and deceitful. These words describe someone who is not genuine and may have ulterior motives. Another synonym could be ambivalent, meaning someone who is unsure or conflicted about their feelings. Having a double heart can lead to trust issues and difficulty building relationships. It is important to be honest and true in order to gain the trust and respect of others. Using synonyms can help express one's thoughts and feelings more accurately and effectively.