The Collaborative International Dictionary of English v.0.48:

Termer \Term"er\, n.
   1. One who resorted to London during the law term only, in
      order to practice tricks, to carry on intrigues, or the
      like. [Obs.] [Written also termor.] --B. Jonson.
      [1913 Webster]

   2. (Law) One who has an estate for a term of years or for
      life.
      [1913 Webster]

WordNet (r) 3.0 (2006):

termer
    n 1: a person who serves a specified term; "there are not many
         fourth termers in the Senate"