sɪnˈsɪə(ɹ) ˈsɒləm ˈsɑləm characterized by a firm and humorless belief in the validity of your opinions both sides were deeply in earnest, even passionate an entirely sincere and cruel tyrant a film with a solemn social message open and genuine; not deceitful he was a good man, decent and sincere felt sincere regret that they were leaving sincere friendship