Source : Webster's Revised Unabridged Dictionary (1913)

Sucker \Suck"er\, v. i.
   To form suckers; as, corn suckers abundantly.

Sucker \Suck"er\ (s[u^]k"[~e]r), n.
   1. One who, or that which, sucks; esp., one of the organs by
      which certain animals, as the octopus and remora, adhere
      to other bodies.

   2. A suckling; a sucking animal. --Beau. & Fl.

   3. The embolus, or bucket, of a pump; also, the valve of a
      pump basket. --Boyle.

   4. A pipe through which anything is drawn.

   5. A small piece of leather, usually round, having a string
      attached to the center, which, when saturated with water
      and pressed upon a stone or other body having a smooth
      surface, adheres, by reason of the atmospheric pressure,
      with such force as to enable a considerable weight to be
      thus lifted by the string; -- used by children as a
      plaything.

   6. (Bot.) A shoot from the roots or lower part of the stem of
      a plant; -- so called, perhaps, from diverting nourishment
      from the body of the plant.

   7. (Zo["o]l.)
      (a) Any one of numerous species of North American
          fresh-water cyprinoid fishes of the family
          {Catostomid[ae]}; so called because the lips are
          protrusile. The flesh is coarse, and they are of
          little value as food. The most common species of the
          Eastern United States are the northern sucker
          ({Catostomus Commersoni}), the white sucker ({C.
          teres}), the hog sucker ({C. nigricans}), and the
          chub, or sweet sucker ({Erimyzon sucetta}). Some of
          the large Western species are called {buffalo fish},
          {red horse}, {black horse}, and {suckerel}.
      (b) The remora.
      (c) The lumpfish.
      (d) The hagfish, or myxine.
      (e) A California food fish ({Menticirrus undulatus})
          closely allied to the kingfish
      (a); -- called also {bagre}.

   8. A parasite; a sponger. See def. 6, above.

            They who constantly converse with men far above
            their estates shall reap shame and loss thereby; if
            thou payest nothing, they will count thee a sucker,
            no branch.                            --Fuller.

   9. A hard drinker; a soaker. [Slang]

   10. A greenhorn; one easily gulled. [Slang, U.S.]

   11. A nickname applied to a native of Illinois. [U. S.]

   {Carp sucker}, {Cherry sucker}, etc. See under {Carp},
      {Cherry}, etc.

   {Sucker fish}. See {Sucking fish}, under {Sucking}.

   {Sucker rod}, a pump rod. See under {Pump}.

   {Sucker tube} (Zo["o]l.), one of the external ambulacral
      tubes of an echinoderm, -- usually terminated by a sucker
      and used for locomotion. Called also {sucker foot}. See
      {Spatangoid}.

Sucker \Suck"er\, v. t. [imp. & p. p. {Suckered}; p. pr. & vb.
   n. {Suckering}.]
   To strip off the suckers or shoots from; to deprive of
   suckers; as, to sucker maize.

Source : WordNet®

sucker
     n 1: a person who is gullible and easy to take advantage of [syn:
           {chump}, {fool}, {gull}, {mark}, {patsy}, {fall guy}, {soft
          touch}, {mug}]
     2: a shoot arising from a plant's roots
     3: a drinker who sucks (as at a nipple or through a straw)
     4: flesh of any of numerous North American food fishes with
        toothless jaws
     5: hard candy on a stick [syn: {lollipop}, {all-day sucker}]
     6: an organ specialized for sucking nourishment or for adhering
        to objects by suction
     7: mostly North American freshwater fishes with a thick-lipped
        mouth for feeding by suction; related to carps