The Collaborative International Dictionary of English v.0.48:

midterm \midterm\ n.
   1. the middle of the gestation period.
      [WordNet 1.5]

   2. The middle of an academic term or a political term in
      office.
      [WordNet 1.5]

   3. An examination given in the middle of an academic term; a
      midterm examination.

   Syn: midterm examination, midterm exam, midterm.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

midterm
    n 1: the middle of the gestation period
    2: middle of an academic term or a political term in office
    3: an examination administered in the middle of an academic term
       [syn: midterm examination, midterm exam, midterm]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "midterm":
   audition, blue book, exam, examen, examination, final,
   final examination, great go, hearing, honors, midsemester, oral,
   oral examination, prelim, quiz, take-home examination, test, trial,
   tripos, viva, written, written examination