The Collaborative International Dictionary of English v.0.48:

Strife \Strife\, n. [OF. estrif. See Strive.]
   1. The act of striving; earnest endeavor. [Archaic] --Shak.
      [1913 Webster]

   2. Exertion or contention for superiority; contest of
      emulation, either by intellectual or physical efforts.
      [1913 Webster]

            Doting about questions and strifes of words. --1
                                                  Tim. vi. 4.
      [1913 Webster]

            Thus gods contended -- noble strife
            Who most should ease the wants of life. --Congreve.
      [1913 Webster]

   3. Altercation; violent contention; fight; battle.
      [1913 Webster]

            Twenty of them fought in this black strife. --Shak.
      [1913 Webster]

            These vows, thus granted, raised a strife above
            Betwixt the god of war and queen of love. --Dryden.
      [1913 Webster]

   4. That which is contended against; occasion of contest.
      [Obs.] "Lamenting her unlucky strife." --Spenser.
      [1913 Webster]

   Syn: Contest; struggle; quarrel. See Contention.
        [1913 Webster]

WordNet (r) 3.0 (2006):

strife
    n 1: lack of agreement or harmony [syn: discord, strife]
    2: bitter conflict; heated often violent dissension

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "strife":
   Kilkenny cats, altercation, animosity, antagonism, arguing,
   argument, bad blood, bicker, bickering, blood feud, brawl, broil,
   cat-and-dog life, combat, competition, conflict, contention,
   contentiousness, contest, contestation, controversy,
   cut and thrust, debate, difference, disagreement, discord,
   disharmony, disputation, dispute, dissension, donnybrook,
   donnybrook fair, embroilment, enmity, feud, fight, fighting,
   fliting, fracas, friction, fuss, hard feelings, hatred, hostility,
   ill will, imbroglio, litigation, logomachy, open quarrel,
   paper war, polemic, quarrel, quarreling, quarrelsomeness, rivalry,
   scrapping, sharp words, slanging match, snarl, spat, squabble,
   squabbling, struggle, tiff, tussle, unfriendliness, vendetta, war,
   war of words, warfare, words, wrangle, wrangling