The noun remorse means a strong feeling of sadness and regret because of the wrong things that have been done.

Synonyms are guilty, grief, shame, or penance.

The word origins from Old French (14th century) remors (Modern French remords), and Medieval Latin remorsum meaning “a biting back or in return”, noun use of neuter past participle of Latin remordere meaning “to vex, torment disturb”, literally “to bite back, bite again” (but seldom used in the literal sense). It comes from re– meaning “back, again” plus mordēre meaning “to bite”.

I feel remorse for leaving you a decade ago.

Remorse can be seen in her face after selling her fake silver necklace to her friend.

She thought the old woman didn’t feel remorse after sending the child for adoption.