The Collaborative International Dictionary of English v.0.48:

Gull \Gull\ (g[u^]l), v. t. [imp. & p. p. Gulled (g[u^]ld); p.
   pr. & vb. n. Gulling.] [Prob. fr. gull the bird; but cf.
   OSw. gylla to deceive, D. kullen, and E. cullibility.]
   To deceive; to cheat; to mislead; to trick; to defraud.
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         The rulgar, gulled into rebellion, armed. --Dryden.
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         I'm not gulling him for the emperor's service.
                                                  --Coleridge.
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The Collaborative International Dictionary of English v.0.48:

Gull \Gull\, n.
   1. A cheating or cheat; trick; fraud. --Shak.
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   2. One easily cheated; a dupe. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Gull \Gull\, n. [Of Celtic origin; cf. Corn. gullan, W. gwylan.]
   (Zool.)
   One of many species of long-winged sea birds of the genus
   Larus and allied genera.
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   Note: Among the best known American species are the herring
         gull (Larus argentatus), the great black-backed gull
         (L. murinus) the laughing gull (L. atricilla), and
         Bonaparte's gull (L. Philadelphia). The common
         European gull is Larus canus.
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   Gull teaser (Zool.), the jager; -- also applied to certain
      species of terns.
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WordNet (r) 3.0 (2006):

gull
    n 1: a person who is gullible and easy to take advantage of
         [syn: chump, fool, gull, mark, patsy, fall guy,
         sucker, soft touch, mug]
    2: mostly white aquatic bird having long pointed wings and short
       legs [syn: gull, seagull, sea gull]
    v 1: make a fool or dupe of [syn: fool, gull, befool]
    2: fool or hoax; "The immigrant was duped because he trusted
       everyone"; "You can't fool me!" [syn: gull, dupe,
       slang, befool, cod, fool, put on, take in, put
       one over, put one across]