Counter-tenor clef

from The Collaborative International Dictionary of English v.0.48

Counter tenor \Coun"ter ten`or\ (t?n`?r). [OF. contreteneur. Cf.
   {Contratenor}, and see {Tenor} a part in music.] (Mus.)
   One of the middle parts in music, between the tenor and the
   treble; high tenor.
   [1913 Webster]

   {Counter-tenor clef} (Mus.), the C clef when placed on the
      third line; -- also called {alto clef}.
      [1913 Webster]