NOUN (2)

1. any hard struggle between equally matched groups;

2. a contest in which teams pull of opposite ends of a rope; the team dragged across a central line loses;

WordNet (r) 3.0 (2006):

tug-of-war
    n 1: any hard struggle between equally matched groups
    2: a contest in which teams pull of opposite ends of a rope; the
       team dragged across a central line loses

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "tug-of-war":
   action, aerial combat, affray, armored combat, attraction, battle,
   battle royal, brush, bullfight, clash, clash of arms, cockfight,
   combat, conflict, dogfight, draft, drawing, drayage, embroilment,
   exchange of blows, extraction, fight, fire fight, fray,
   ground combat, hand-to-hand combat, hand-to-hand fight, haulage,
   hauling, heaving, house-to-house combat, naval combat,
   passage of arms, pitched battle, pull, pulling, pulling power,
   quarrel, rumble, running fight, scramble, scrimmage, scuffle,
   shoving match, skirmish, stand-up fight, street fight, struggle,
   tauromachy, towage, towing, traction, tractive power, tugging,
   tussle