Penitent
/ˈpɛnɪtənt/
noun
One who repents of sin; one sorrowful on account of his or her transgressions.
One under church censure, but admitted to penance; one undergoing penance.
One under the direction of a confessor.
Synonyms: penaunt
adjective
Feeling pain or sorrow on account of one's sins or offenses; feeling sincere guilt.
Doing penance.