sincere

adjective

1
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
2
open and genuine; not deceitful
he was a good man, decent and sincere
felt sincere regret that they were leaving

Also useful for “sincere”:Unscrambler— Rearrange the letters in “sincere”