The Collaborative International Dictionary of English v.0.48:

Judas \Ju"das\, n.
   The disciple who betrayed Christ. Hence: A treacherous
   person; one who betrays under the semblance of friendship. --
   a. Treacherous; betraying.
   [1913 Webster]

   Judas hole, a peephole or secret opening for spying.

   Judas kiss,
   (a) a deceitful and treacherous kiss.
   (b) an act appearing to be an act of friendship, which is in
       fact harmful to the recipient.

   Judas tree (Bot.), a leguminous tree of the genus Cercis,
      with pretty, rose-colored flowers in clusters along the
      branches. Judas is said to have hanged himself on a tree
      of this genus (Cercis Siliquastrum). Cercis Canadensis
      and Cercis occidentalis are the American species, and
      are called also redbud.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Judas
    n 1: (New Testament) supposed brother of St. James; one of the
         Apostles who is invoked in prayer when a situation seems
         hopeless [syn: Jude, Saint Jude, St. Jude, Judas,
         Thaddaeus]
    2: (New Testament) the Apostle who betrayed Jesus to his enemies
       for 30 pieces of silver [syn: Judas, Judas Iscariot]
    3: someone who betrays under the guise of friendship
    4: a one-way peephole in a door

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "Judas":
   Benedict Arnold, Brutus, Judas Iscariot, Quisling, archtraitor,
   betrayer, cockatrice, conniver, conspirator, conspirer, convict,
   criminal, crook, deceiver, desperado, desperate criminal,
   double agent, double-crosser, double-dealer, felon, fugitive,
   gallows bird, gangster, gaolbird, informer, intrigant, intriguer,
   jailbird, lawbreaker, machinator, mobster, outlaw, plotter,
   public enemy, quisling, racketeer, rat, schemer, scofflaw, serpent,
   snake, swindler, thief, thug, timeserver, traitor, treasonist,
   trimmer, turncoat, two-timer



Easton's 1897 Bible Dictionary:

Judas
   the Graecized form of Judah. (1.) The patriarch (Matt. 1:2, 3).

     (2.) Son of Simon (John 6:71; 13:2, 26), surnamed Iscariot,
   i.e., a man of Kerioth (Josh. 15:25). His name is uniformly the
   last in the list of the apostles, as given in the synoptic
   (i.e., the first three) Gospels. The evil of his nature probably
   gradually unfolded itself till "Satan entered into him" (John
   13:27), and he betrayed our Lord (18:3). Afterwards he owned his
   sin with "an exceeding bitter cry," and cast the money he had
   received as the wages of his iniquity down on the floor of the
   sanctuary, and "departed and went and hanged himself" (Matt.
   27:5). He perished in his guilt, and "went unto his own place"
   (Acts 1:25). The statement in Acts 1:18 that he "fell headlong
   and burst asunder in the midst, and all his bowels gushed out,"
   is in no way contrary to that in Matt. 27:5. The sucide first
   hanged himself, perhaps over the valley of Hinnom, "and the rope
   giving way, or the branch to which he hung breaking, he fell
   down headlong on his face, and was crushed and mangled on the
   rocky pavement below."

     Why such a man was chosen to be an apostle we know not, but it
   is written that "Jesus knew from the beginning who should betray
   him" (John 6:64). Nor can any answer be satisfactorily given to
   the question as to the motives that led Judas to betray his
   Master. "Of the motives that have been assigned we need not care
   to fix on any one as that which simply led him on. Crime is, for
   the most part, the result of a hundred motives rushing with
   bewildering fury through the mind of the criminal."

     (3.) A Jew of Damascus (Acts 9:11), to whose house Ananias was
   sent. The street called "Straight" in which it was situated is
   identified with the modern "street of bazaars," where is still
   pointed out the so-called "house of Judas."

     (4.) A Christian teacher, surnamed Barsabas. He was sent from
   Jerusalem to Antioch along with Paul and Barnabas with the
   decision of the council (Acts 15:22, 27, 32). He was a "prophet"
   and a "chief man among the brethren."


Hitchcock's Bible Names Dictionary (late 1800's):

Judas, Jude, same as Judah