The Collaborative International Dictionary of English v.0.48:

Frater \Fra"ter\, n. [L., a brother.] (Eccl.)
   A monk; also, a frater house. [R.] --Shipley.
   [1913 Webster]

   Frater house, an apartament in a convent used as an eating
      room; a refectory; -- called also a fratery.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

FRATER. A brother. Vide Brother.