The Collaborative International Dictionary of English v.0.48:

Executable \Ex"e*cu`ta*ble\, a.
   Capable of being executed; feasible; as, an executable
   project. [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

executable
    adj 1: capable of being done with means at hand and
           circumstances as they are [syn: feasible, executable,
           practicable, viable, workable]

The Free On-line Dictionary of Computing (30 December 2018):

executable

    A binary file containing a program in
   machine language which is ready to be executed (run).

   The term might also be, but generally isn't, applied to
   scripts which are interpreted by a command line
   interpreter.  Executables are distinguished in Unix by
   having the execute permission bits set, at least for the
   owner.  MS-DOS uses the filename extension ".exe".

   (1997-06-21)