rueful
conscience-stricken, contrite, dismal, doleful, grievous, lugubrious, melancholy, mournful, penitent, pitiable, pitiful, plaintive, regretful, remorseful, repentant, sad, self-reproachful, sorrowful, sorry, woebegone, woeful
Antonyms
cheerful, delighted, glad, happy, joyful, pleased, unrepentant