Source : Webster's Revised Unabridged Dictionary (1913)

Extern \Ex*tern"\, a. [Cf. F. externe. See {External}.]
   External; outward; not inherent. [Obs.] --Shak.

Extern \Ex*tern"\, n. [Cf. F. externe.]
   1. A pupil in a seminary who lives without its walls; a day
      scholar.

   2. Outward form or part; exterior. [R.]

Source : WordNet®

extern
     n : a nonresident doctor or medical student; connected with a
         hospital but not living there [syn: {medical extern}]