[adj] 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"
[adj] open and genuine; not deceitful; "he was a good man, decent and sincere"; "felt sincere regret that they were leaving"; "sincere friendship"
Synonyms
bona fide, cordial, dear, devout, earnest, fervent, genuine, heartfelt, heart-whole, honest, in earnest(p), serious, solemn, true(a), unfeigned, wholehearted, whole-souled