The Collaborative International Dictionary of English v.0.48:

Auger \Au"ger\, n. [OE. augoure, nauger, AS. nafeg[=a]r, fr.
   nafu, nafa, nave of a wheel + g[=a]r spear, and therefore
   meaning properly and originally a nave-bore. See Nave (of a
   wheel) and 2d Gore, n.]
   1. A carpenter's tool for boring holes larger than those
      bored by a gimlet. It has a handle placed crosswise by
      which it is turned with both hands. A pod auger is one
      with a straight channel or groove, like the half of a bean
      pod. A screw auger has a twisted blade, by the spiral
      groove of which the chips are discharge.
      [1913 Webster]

   2. An instrument for boring or perforating soils or rocks,
      for determining the quality of soils, or the nature of the
      rocks or strata upon which they lie, and for obtaining
      water.
      [1913 Webster]

   Auger bit, a bit with a cutting edge or blade like that of
      an anger.
      [1913 Webster]

WordNet (r) 3.0 (2006):

auger
    n 1: a long flexible steel coil for dislodging stoppages in
         curved pipes [syn: plumber's snake, auger]
    2: hand tool for boring holes [syn: auger, gimlet, screw
       auger, wimble]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "auger":
   aculeus, acumination, bit, bore, bore bit, borer, brace and bit,
   breast auger, breast drill, broach, burr, chamfer bit, corkscrew,
   cross bit, cusp, diamond drill, drill, drill press, gimlet,
   hand drill, keyway drill, mucro, neb, needle, nib, point,
   portable drill, posthole auger, power drill, prick, prickle,
   pump drill, ratchet drill, reamer, rotary drill, star drill, sting,
   strap drill, tap, tip, trepan, trephine, twist bit, twist drill,
   wimble