The Collaborative International Dictionary of English v.0.48:

Intern \In*tern"\, a. [L. internus: cf. F. interne. See
   Internal.]
   Internal. [Obs.] --Howell.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Intern \In*tern"\, v. t. [F. interne. See Intern, a.]
   1. To put for safe keeping in the interior of a place or
      country; to confine to one locality; as, to intern troops
      which have fled for refuge to a neutral country.
      [1913 Webster]

   2. To hold until the end of a war, as enemy citizens in a
      country at the time of outbreak of hostilities; -- an
      action performed by countries.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

intern \in*tern"\, n. [F.] (F. pron. [a^]N`t[^a]rn")
   1. (Med.) A resident physician in a hospital, especially one
      who has recently received the Doctorate and is practising
      under supervision of experienced physicians, as a
      continuation of the training process; a house physician;
      also called houseman in Britain. [Also spelled
      interne.]
      [Webster 1913 Suppl. +PJC]

   2. A person working as an apprentice to gain experience in an
      occupation; sometimes the position is paid a salary, and
      other times it is not; as, a white house intern; an intern
      in a law firm.
      [PJC]

WordNet (r) 3.0 (2006):

intern
    n 1: an advanced student or graduate in medicine gaining
         supervised practical experience (`houseman' is a British
         term) [syn: intern, interne, houseman, medical
         intern]
    v 1: deprive of freedom; "During WW II, Japanese were interned
         in camps in the West"
    2: work as an intern; "The young doctor is interning at the
       Medical Center this year"