source language

from WordNet (r) 3.0 (2006)

source language
    n 1: a language that is to be translated into another language

from The Free On-line Dictionary of Computing (8 July 2008)

source code
source
source language

   <language, programming> (Or "source", or rarely "source
   language") The form in which a computer program is written by
   the programmer.  Source code is written in some formal
   programming language which can be compiled automatically into
   {object code} or {machine code} or executed by an
   {interpreter}.

   (1995-01-05)