The Collaborative International Dictionary of English v.0.48:

Rebel \Re*bel"\ (r[-e]*b[e^]l"), v. i. [imp. & p. p. Rebelled
   (r[-e]*b[e^]ld); p. pr. & vb. n. Rebelling.] [F. rebeller,
   fr. L. rebellare to make war again; pref. re- again + bellare
   to make war, fr. bellum war. See Bellicose, and cf. Revel
   to carouse.]
   1. To renounce, and resist by force, the authority of the
      ruler or government to which one owes obedience. See
      Rebellion.
      [1913 Webster]

            The murmur and the churls' rebelling. --Chaucer.
      [1913 Webster]

            Ye have builded you an altar, that ye might rebel
            this day against the Lord.            --Josh. xxii.
                                                  16.
      [1913 Webster]

   2. To be disobedient to authority; to assume a hostile or
      insubordinate attitude; to revolt.
      [1913 Webster]

            How could my hand rebel against my heart?
            How could your heart rebel against your reason?
                                                  --Dryden.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rebel \Reb"el\ (r[e^]b"[e^]l), a. [F. rebelle, fr. L. rebellis.
   See Rebel, v. i.]
   Pertaining to rebels or rebellion; acting in revolt;
   rebellious; as, rebel troops.
   [1913 Webster]

         Whoso be rebel to my judgment.           --Chaucer.
   [1913 Webster]

         Convict by flight, and rebel to all law. --Milton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rebel \Reb"el\, n. [F. rebelle.]
   One who rebels.
   [1913 Webster]

   Syn: Revolter; insurgent.

   Usage: Rebel, Insurgent. Insurgent marks an early, and
          rebel a more advanced, stage of opposition to
          government. The former rises up against his rulers,
          the latter makes war upon them.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Rebel
    n 1: `Johnny' was applied as a nickname for Confederate soldiers
         by the Federal soldiers in the American Civil War;
         `greyback' derived from their grey Confederate uniforms
         [syn: Rebel, Reb, Johnny Reb, Johnny, greyback]
    2: a person who takes part in an armed rebellion against the
       constituted authority (especially in the hope of improving
       conditions) [syn: insurgent, insurrectionist, freedom
       fighter, rebel]
    3: someone who exhibits great independence in thought and action
       [syn: maverick, rebel]
    v 1: take part in a rebellion; renounce a former allegiance
         [syn: rebel, arise, rise, rise up]
    2: break with established customs [syn: rebel, renegade]

Moby Thesaurus II by Grady Ward, 1.0:

138 Moby Thesaurus words for "rebel":
   Bolshevik, Bolshevist, Bolshie, Carbonarist, Carbonaro, Castroist,
   Castroite, Charley, Communist, Cong, Fenian, Guevarist, Jacobin,
   Leninist, Maoist, Marxist, Mau-Mau, Puritan, Red, Red Republican,
   Roundhead, Sinn Feiner, Trotskyist, Trotskyite, VC, Vietcong,
   Yankee, Yankee Doodle, adversary, agitator, anarch, anarchist,
   anarcho-syndicalist, antagonist, antinomian, apostate, arise,
   assailant, attacker, bellyacher, bonnet rouge, brawler, breakaway,
   challenge, complainant, complainer, crab, crank,
   criminal syndicalist, croaker, dare, debunker, defy, disobey,
   dissent, dissenter, extreme, extremist, extremistic, factious,
   faultfinder, flout, frondeur, griper, grouch, grouser, growler,
   grumbler, heretic, iconoclast, insubordinate, insurge, insurgent,
   insurrect, insurrectionary, insurrectionist, insurrecto, kicker,
   kvetch, malcontent, maverick, mount the barricades, murmurer,
   mutineer, mutineering, mutinous, mutiny, mutterer, nihilist,
   nonconformist, opponent, overthrow, querulous person, radical,
   reactionary, reactionist, rebellious, recusant, red, reluct,
   reluctate, resistance fighter, resister, revolt, revolter,
   revolute, revolution, revolutional, revolutionary,
   revolutionary junta, revolutioner, revolutionist, revolutionize,
   revolutionizer, riot, rioter, riotous, rise, rise against, rise up,
   run riot, sans-culotte, sans-culottist, schismatic, seditionary,
   seditious, sorehead, strike, subversive, subvert, syndicalist,
   terrorist, traitor, traitorous, treasonable, turbulent, ultraist,
   whiner



The Devil's Dictionary (1881-1906):

REBEL, n.  A proponent of a new misrule who has failed to establish
it.