Source : Webster's Revised Unabridged Dictionary (1913)

Monkey \Mon"key\, n.; pl. {Monkeys}. [Cf. OIt. monicchio, It.
   monnino, dim. of monna an ape, also dame, mistress, contr.
   fr. madonna. See {Madonna}.]
   1. (Zo["o]l.)
      (a) In the most general sense, any one of the Quadrumana,
          including apes, baboons, and lemurs.
      (b) Any species of Quadrumana, except the lemurs.
      (c) Any one of numerous species of Quadrumana (esp. such
          as have a long tail and prehensile feet) exclusive of
          apes and baboons.

   Note: The monkeys are often divided into three groups: ({a})
         {Catarrhines}, or {Simid[ae]}. These have an oblong
         head, with the oblique flat nostrils near together.
         Some have no tail, as the apes. All these are natives
         of the Old World. ({b}) {Platyrhines}, or {Cebid[ae]}.
         These have a round head, with a broad nasal septum, so
         that the nostrils are wide apart and directed downward.
         The tail is often prehensile, and the thumb is short
         and not opposable. These are natives of the New World.
         ({c}) {Strepsorhines}, or {Lemuroidea}. These have a
         pointed head with curved nostrils. They are natives of
         Southern Asia, Africa, and Madagascar.

   2. A term of disapproval, ridicule, or contempt, as for a
      mischievous child.

            This is the monkey's own giving out; she is
            persuaded I will marry her.           --Shak.

   3. The weight or hammer of a pile driver, that is, a very
      heavy mass of iron, which, being raised on high, falls on
      the head of the pile, and drives it into the earth; the
      falling weight of a drop hammer used in forging.

   4. A small trading vessel of the sixteenth century.

   {Monkey boat}. (Naut.)
      (a) A small boat used in docks.
      (b) A half-decked boat used on the River Thames.

   {Monkey block} (Naut.), a small single block strapped with a
      swivel. --R. H. Dana, Jr.

   {Monkey flower} (Bot.), a plant of the genus {Mimulus}; -- so
      called from the appearance of its gaping corolla. --Gray.

   {Monkey gaff} (Naut.), a light gaff attached to the topmast
      for the better display of signals at sea.

   {Monkey jacket}, a short closely fitting jacket, worn by
      sailors.

   {Monkey rail} (Naut.), a second and lighter rail raised about
      six inches above the quarter rail of a ship.

   {Monkey shine}, monkey trick. [Slang, U.S.]

   {Monkey trick}, a mischievous prank. --Saintsbury.

   {Monkey wheel}. See {Gin block}, under 5th {Gin}.

   {Monkey wrench}, a wrench or spanner having a movable jaw.