The Collaborative International Dictionary of English v.0.48:

Extramural \Ex`tra*mu"ral\, a.
   1. Outside of the walls, as of a fortified or walled city.
      [1913 Webster]

   2. pertaining to activities, such as sports contests, that
      involve representatives from more than one school.
      [PJC]

WordNet (r) 3.0 (2006):

extramural
    adj 1: carried on outside the bounds of an institution or
           community; "extramural sports" [ant: intramural]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "extramural":
   academic, alien, classroom, collegiate, exterrestrial,
   exterritorial, extragalactic, extralateral, extraliminal,
   extramundane, extrapolar, extraprovincial, extrasolar,
   extraterrestrial, extraterritorial, extratribal, foreign,
   interscholastic, intramural, outlandish, preschool, scholastic,
   school, university