21 synonyms for heartfelt such as cordial, ardent, and bona fide. Heartfelt is an adjective, and its antonyms are insincere and apathetic.
Ardent, bona fide, cordial, deep, deeply felt, eager, earnest, enthusiastic, fervent, from the heart, full-hearted, genuine, honest, kindly, passionate, profound, sincere, unfeigned, warm, and wholehearted.