Decanicum (Decania, or Decanica) was an ecclesiastical prison in which criminal clerks were incarcerated by their ecclesiastical superiors. The word is derived from the decani, who were jailers. By a false etymology it is sometimes written dicaincum and diaconicum. The clergy, instead of being beheaded or hung for misdemeanors, had suspended from their necks the gospels and the cross, and were imprisoned in one of the decanica of the church. The heretics, by a decree of Arcadius and Honorius; were deprived, with other buildings, of the decanica. See Smith, Dict. of Christ. Antiq. s.v.