confiteor
noun
con·fi·te·or kən-ˈfē-tē-ˌȯr 
-ər
: a liturgical form in which sinfulness is acknowledged and intercession for God's mercy requested
Word History
Etymology
Middle English, from Medieval Latin confiteor domino meo "I confess [my sins] to the Lord," the opening words of the form; confiteor, first person singular present tense of confitērī "to admit (the truth of a statement), confess"
First Known Use
13th century, in the meaning defined above