1) Latin religious phrase 
The Confiteor (so named from its first word, or incipit, in Latin, meaning `I confess` or `I acknowledge`) is one of the prayers that can be said during the Penitential Act at the beginning of Mass of the Roman Rite in the Catholic Church. It is also said in the Lutheran Church at the beginning of their Divine Service, and by some Anglo-cathol...
prayer of confession of sins
• (n.) A form of prayer in which public confession of sins is made.
Con·fit'e·or noun [ Latin , I confess. See Confess .] (R.C.Ch.) A form of prayer in which public confession of sins is made. 
a prayer in the form of a general confession said at the beginning of the Mass and on certain other occasions.