The Collaborative International Dictionary of English v.0.48:

Skirmish \Skir"mish\, v. i. [imp. & p. p. Skirmished; p. pr. &
   vb. n. Skirmishing.] [OE. skirmishen, scarmishen, OF.
   escremir, eskermir, to fence, fight, F. escrimer, of German
   origin; cf. OHG. scirmen to protect, defend, G. schirmen,
   OHG. scirm, scerm, protection, shield, G. schirm; perhaps
   akin to Gr. ???? a sunshade. Cf. Scaramouch, Scrimmage.]
   To fight slightly or in small parties; to engage in a
   skirmish or skirmishes; to act as skirmishers.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Skirmish \Skir"mish\, n.[OE. scarmishe, scrymishe. See
   Skirmish, v. i.]
   1. A slight fight in war; a light or desultory combat between
      detachments from armies, or between detached and small
      bodies of troops.
      [1913 Webster]

   2. A slight contest.
      [1913 Webster]

            They never meet but there's a skirmish of wit.
                                                  --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

skirmish
    n 1: a minor short-term fight [syn: brush, clash,
         encounter, skirmish]
    v 1: engage in a skirmish

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "skirmish":
   action, aerial combat, affray, ambush, armored combat, assault,
   attack, battle, battle royal, box, brawl, broil, brush, bullfight,
   clash, clash of arms, close, cockfight, collide, combat,
   come to blows, conflict, confrontation, contend, contest,
   cut and thrust, dogfight, duel, embroilment, encounter, engagement,
   exchange blows, exchange of blows, fence, feud, fight,
   fight a duel, fire fight, fracas, fray, give and take,
   give satisfaction, grapple, grapple with, ground combat,
   hand-to-hand combat, hand-to-hand fight, house-to-house combat,
   jostle, joust, melee, mix it up, naval combat, passage of arms,
   pitched battle, quarrel, rassle, riot, rumble, run a tilt, run-in,
   running fight, scramble, scrap, scrimmage, scuffle, set-to,
   shoving match, showdown, spar, stand-up fight, street fight,
   strive, struggle, tauromachy, thrust and parry, tilt, tourney,
   tug-of-war, tussle, wage war, war, wrestle