Feeling pain or sorrow on account of sins or offenses; repentant; contrite; sincerely affected by a sense of guilt, and resolved on amendment of life.(adjective)
source: webster1913
noun (n)
(Roman Catholic Church) a person who repents for wrongdoing (a Roman Catholic may be admitted to penance under the direction of a confessor)(noun.person)
source: wordnet30
One who repents of sin; one sorrowful on account of his transgressions.(noun)