The Collaborative International Dictionary of English v.0.48:

Cut-off \Cut"-off`\ (k[u^]t"[o^]f`; 115), n.
   1. That which cuts off or shortens, as a nearer passage or
      road.
      [1913 Webster]

   2. (Mach.)
      (a) The valve gearing or mechanism by which steam is cut
          off from entering the cylinder of a steam engine after
          a definite point in a stroke, so as to allow the
          remainder of the stroke to be made by the expansive
          force of the steam already let in. See Expansion
          gear, under Expansion.
      (b) Any device for stopping or changing a current, as of
          grain or water in a spout.
          [1913 Webster]

WordNet (r) 3.0 (2006):

cutoff
    n 1: a designated limit beyond which something cannot function
         or must be terminated
    2: a route shorter than the usual one [syn: shortcut,
       cutoff, crosscut]
    3: a device that terminates the flow in a pipe

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "cutoff":
   air line, arrest, beeline, bell, border line, bound, boundary,
   boundary condition, boundary line, bourn, break boundary,
   breakoff point, ceiling, check, checkmate, circumscription,
   compass, confine, cut, cutoff point, dead stop, deadline, deadlock,
   delimitation, determinant, division line, end, endgame, ending,
   extremity, final whistle, finish, floor, frontier, full stop,
   grinding halt, gun, halt, hedge, high-water mark, interface, limen,
   limit, limitation, limiting factor, line, line of demarcation,
   lockout, low-water mark, lower limit, march, mark, mete, shortcut,
   shortest way, sit-down strike, stalemate, stand, standoff,
   standstill, start, starting line, starting point, stay, stop,
   stoppage, strike, target date, term, terminal date, terminus,
   threshold, time allotment, upper limit, walkout, work stoppage