The Collaborative International Dictionary of English v.0.48:

Pro \Pro\, prep. [L.; akin to prae before, Gr. ?, and E. for.
   See For, prep., and cf. Prior, a.]
   A Latin preposition signifying for, before, forth.
   [1913 Webster]

   Pro confesso [L.] (Law), taken as confessed. The action of
      a court of equity on that portion of the pleading in a
      particular case which the pleading on the other side does
      not deny.

   Pro rata. [L. See Prorate.] In proportion; proportion.

   Pro re nata [L.] (Law), for the existing occasion; as
      matters are.
      [1913 Webster]

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

PRO CONFESSO, chan. pract. For confessed.
     2. When the defendant has been served personally with a subpoena, or
when not being so served has appeared, and afterwards neglects to answer the
matter contained in the bill, it shall be taken pro confesso, as if the
matter were confessed by the defendant. Blake's Ch. Pr. 80; Newl. Ch. Pr. c.
1, s. 12; 1 Johns. Cb. Rep. 8. It also be taken pro confesso if the manner
is sufficient. 4 Vin. Ab. 446 2 Atk. 24 3 Ves. 209; Harr. Ch. Pr. 154. Vide
4 Ves. 619, and the cases there cited.