The Collaborative International Dictionary of English v.0.48:

Tenaille \Te*naille"\, n. [F., a pair of pincers or tongs, a
   tenaille, fr. L. tenaculum. See Tenaculum.] (Fort.)
   An outwork in the main ditch, in front of the curtain,
   between two bastions. See Illust. of Ravelin.
   [1913 Webster]