double-threaded

from The Collaborative International Dictionary of English v.0.48

Double-threaded \Dou"ble-thread`ed\, a.
   1. Consisting of two threads twisted together; using two
      threads.
      [1913 Webster]

   2. (Mech.) Having two screw threads instead of one; -- said
      of a screw in which the pitch is equal to twice the
      distance between the centers of adjacent threads.
      [1913 Webster]