The Collaborative International Dictionary of English v.0.48:

guy \guy\, v. t. [imp. & p. p. guyed (g[imac]d); p. pr. & vb.
   n. guying.]
   To steady or guide with a guy.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

guy \guy\, n.
   1. A grotesque effigy, like that of Guy Fawkes, dressed up in
      England on the fifth of November, the day of the Gunpowder
      Plot.
      [1913 Webster]

            The lady . . . who dresses like a guy. --W. S.
                                                  Gilbert.
      [1913 Webster]

   2. Hence: A person of queer looks or dress. [Chiefly Brit.
      slang] --Dickens.
      [1913 Webster]

   3. A man or young man; a fellow; -- usually contrasted with
      gals or girls as, it was fun for both the guys and
      gals; the guys were watching football while the girls
      played bridge. [Informal]
      [PJC]

   4. A member of a group of either sex, usually a friend or
      comrade; -- usually used in the pl.; as, tell the guys to
      come inside; are any of you guys interested in a game of
      tennis?. [Informal]
      [PJC]

   great guy a man who has a very pleasant personality,
      typically one who is friendly, generous, and pleasant to
      associate with.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

guy \guy\ (g[imac]), n. [Sp. guia guide, a guy or small rope
   used on board of ships to keep weighty things in their
   places; of Teutonic origin, and the same word as E. guide.
   See Guide, and cf. Gye.]
   A rope, chain, or rod attached to anything to steady it; as:
   a rope to steady or guide an object which is being hoisted or
   lowered; a rope which holds in place the end of a boom, spar,
   or yard in a ship; a chain or wire rope connecting a
   suspension bridge with the land on either side to prevent
   lateral swaying; a rod or rope attached to the top of a
   structure, as of a derrick, and extending obliquely to the
   ground, where it is fastened.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Guy \Guy\, v. t.
   To fool; to baffle; to make (a person) an object of ridicule.
   [Local & Collog U.S.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

guy
    n 1: an informal term for a youth or man; "a nice guy"; "the
         guy's only doing it for some doll" [syn: guy, cat,
         hombre, bozo]
    2: an effigy of Guy Fawkes that is burned on a bonfire on Guy
       Fawkes Day
    3: a cable, wire, or rope that is used to brace something
       (especially a tent) [syn: guy, guy cable, guy wire,
       guy rope]
    v 1: subject to laughter or ridicule; "The satirists ridiculed
         the plans for a new opera house"; "The students poked fun
         at the inexperienced teacher"; "His former students roasted
         the professor at his 60th birthday" [syn: ridicule,
         roast, guy, blackguard, laugh at, jest at, rib,
         make fun, poke fun]
    2: steady or support with a guy wire or cable; "The Italians
       guyed the Tower of Pisa to prevent it from collapsing"