Antonyms of adj heartfelt

1 sense of heartfelt

Sense 1
dear, devout, earnest, heartfelt -- (earnest; "one's dearest wish"; "devout wishes for their success"; "heartfelt condolences")

INDIRECT (VIA sincere) -> insincere -- (lacking sincerity; "a charming but thoroughly insincere woman"; "their praise was extravagant and insincere")

Similarity of adj heartfelt

1 sense of heartfelt

Sense 1
dear, devout, earnest, heartfelt -- (earnest; "one's dearest wish"; "devout wishes for their success"; "heartfelt condolences")
       => sincere (vs. insincere) -- (open and genuine; not deceitful; "he was a good man, decent and sincere"; "felt sincere regret that they were leaving"; "sincere friendship")