The Collaborative International Dictionary of English v.0.48:

foxhole \foxhole\ n. (Mil.)
   a small pit in the ground for individual shelter against
   enemy fire.

   Syn: fox hole.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

foxhole
    n 1: a small dugout with a pit for individual shelter against
         enemy fire [syn: foxhole, fox hole]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "foxhole":
   abri, air-raid shelter, antre, approach trench, asylum, bolt-hole,
   bomb shelter, bombproof, bunker, burrow, cache, cave, cavern,
   communication trench, concealment, corner, countermine, coupure,
   cove, cover, covert, coverture, cranny, cubby, cubbyhole,
   cyclone cellar, dark corner, den, ditch, double sap, dugout, earth,
   entrenchment, fallout shelter, fire trench, flying sap,
   fortified tunnel, fosse, funk hole, gallery, grot, grotto,
   hideaway, hideout, hidey hole, hiding, hiding place, hole, lair,
   mine, moat, niche, nook, parallel, recess, refuge, retreat,
   safety zone, sanctuary, sap, secret place, sewer, shelter,
   slit trench, stash, storm cave, storm cellar, subterrane, subway,
   trench, tunnel, undercovert, warren