The Collaborative International Dictionary of English v.0.48:

Nose \Nose\ (n[=o]z), n. [AS. nosu; akin to D. neus, G. nase,
   OHG. nasa, Icel. n["o]s, Sw. n[aum]sa, Dan. n[aum]se, Lith.
   nosis, Russ. nos', L. nasus, nares, Skr. n[=a]s[=a], n[=a]s.
   [root]261. Cf. Nasal, Nasturtium, Naze, Nostril,
   Nozzle.]
   [1913 Webster]
   1. (Anat.) The prominent part of the face or anterior
      extremity of the head containing the nostrils and
      olfactory cavities; the olfactory organ. See Nostril,
      and Olfactory organ under Olfactory.
      [1913 Webster]

   2. The power of smelling; hence, scent.
      [1913 Webster]

            We are not offended with a dog for a better nose
            than his master.                      --Collier.
      [1913 Webster]

   3. A projecting end or beak at the front of an object; a
      snout; a nozzle; a spout; as, the nose of a bellows; the
      nose of a teakettle.
      [1913 Webster]

   Nose bit (Carp.), a bit similar to a gouge bit, but having
      a cutting edge on one side of its boring end.

   Nose hammer (Mach.), a frontal hammer.

   Nose hole (Glass Making), a small opening in a furnace,
      before which a globe of crown glass is held and kept soft
      at the beginning of the flattening process.

   Nose key (Carp.), a fox wedge.

   Nose leaf (Zool.), a thin, broad, membranous fold of skin
      on the nose of many species of bats. It varies greatly in
      size and form.

   Nose of wax, (fig.), a person who is pliant and easily
      influenced. "A nose of wax to be turned every way."
      --Massinger

   Nose piece, the nozzle of a pipe, hose, bellows, etc.; the
      end piece of a microscope body, to which an objective is
      attached.

   To hold one's nose to the grindstone, To put one's nose to
   the grindstone, or To bring one's nose to the grindstone.
      See under Grindstone.

   To lead by the nose, to lead at pleasure, or to cause to
      follow submissively; to lead blindly, as a person leads a
      beast. --Shak.

   To put one's nose out of joint, to humiliate one's pride,
      esp. by supplanting one in the affections of another.
      [Slang]

   To thrust one's nose into, to meddle officiously in.

   To wipe one's nose of, to deprive of; to rob. [Slang]

   on the nose,
      (a) exactly, accurately.
      (b) (racing) to win, as opposed to to place or to
          show.
          [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

on the nose
    adv 1: just as it should be; "`Precisely, my lord,' he said"
           [syn: precisely, exactly, on the nose, on the
           dot, on the button]
    adj 1: being precise with regard to a prescribed or specified
           criterion; "his guess was on the nose"; "the prediction
           for snow was right on the button" [syn: on the nose,
           on the button]