The Collaborative International Dictionary of English v.0.48:

Parathesis \Pa*rath"e*sis\, n.; pl. Paratheses. [NL., from Gr.
   ? a putting beside, from ? to put beside.]
   [1913 Webster]
   1. (Gram.) The placing of two or more nouns in the same case;
      apposition.
      [1913 Webster]

   2. (Rhet.) A parenthetical notice, usually of matter to be
      afterward expanded. --Smart.
      [1913 Webster]

   3. (Print.) The matter contained within brackets.
      [1913 Webster]

   4. (Eccl.) A commendatory prayer. --Shipley.
      [1913 Webster]