The Collaborative International Dictionary of English v.0.48:

Bolshevik \Bolshevik\ adj.
   of or pertaining to Bolsheviks or bolshevism. Bolshevik
   Revolution

   Syn: bolshevik.
        [WordNet 1.5] bolshevise

The Collaborative International Dictionary of English v.0.48:

Bolshevik \Bolshevik\ n. [Russian bol'shevik fr. bol'she more +
   -vik, a person, i.e. one who is a member of the majority (in
   the revolutionary Russian parliament).]
   1. a member of the extreme left wing of the Social Democratic
      Party that seized power in Russia in 1917 after the
      Russian October Revolution, and advocated rule by the
      proletariat and state ownership of property.

   Note: Actually in the minority, this branch seized the
         opportunity, when the moderate group walked out, to
         proclaim themselves a majority and form a government.
         They prevailed in the subsequent civil war.
         [PJC]

   2. same as communist, especially used of Russian
      communists.
      [PJC]

   3. anyone with communist leanings or sympathies; -- used very
      loosely in a derogatory sense by some people with
      economically conservative views.
      [PJC]

WordNet (r) 3.0 (2006):

Bolshevik
    adj 1: of or relating to Bolshevism; "Bolshevik Revolution"
           [syn: Bolshevik, Bolshevist, Bolshevistic]
    n 1: emotionally charged terms used to refer to extreme radicals
         or revolutionaries [syn: Bolshevik, Marxist, red,
         bolshie, bolshy]
    2: a Russian member of the left-wing majority group that
       followed Lenin and eventually became the Russian communist
       party [syn: Bolshevik, Bolshevist]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "Bolshevik":
   Bolshevist, Bolshie, Carbonarist, Carbonaro, Castroist, Castroite,
   Charley, Communist, Communist sympathizer, Cong, Fenian, Guevarist,
   Jacobin, Leninist, Maoist, Marxist, Marxist-Leninist, Mau-Mau,
   Puritan, Red, Red Republican, Roundhead, Sinn Feiner, Stalinist,
   Titoist, Trotskyist, Trotskyite, VC, Vietcong, Wobbly, Yankee,
   Yankee Doodle, anarch, anarchist, anarcho-syndicalist,
   avowed Communist, bolshie, bonnet rouge, commie, comrade,
   criminal syndicalist, extreme left-winger, extremist,
   fellow traveler, left-wing extremist, lunatic fringe, mild radical,
   nihilist, parlor Bolshevik, parlor pink, pink, pinko, radical,
   rebel, red, revisionist, revolutionary, revolutionary junta,
   revolutioner, revolutionist, revolutionizer, sans-culotte,
   sans-culottist, subversive, syndicalist, terrorist, ultra,
   ultraist, yippie