The Collaborative International Dictionary of English v.0.48:

Executory \Ex*ec"u*to*ry\, a. [LL. executorius, L. exsecutorius:
   cf.F. ex['e]cutoire.]
   1. Pertaining to administration, or putting the laws in
      force; executive.
      [1913 Webster]

            The official and executory duties of government.
                                                  --Burke.
      [1913 Webster]

   2. (Law) Designed to be executed or carried into effect in
      time to come, or to take effect on a future contingency;
      as, an executory devise, reminder, or estate; an executory
      contract. --Blackstone.
      [1913 Webster]

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

EXECUTORY. Whatever may be executed; as an executory sentence or judgment,
an executory contract.