The Collaborative International Dictionary of English v.0.48:

Excavation \Ex`ca*va"tion\, n. [L. excavatio: cf. F.
   excavation.]
   1. The act of excavating, or of making hollow, by cutting,
      scooping, or digging out a part of a solid mass.
      [1913 Webster]

   2. A cavity formed by cutting, digging, or scooping. "A
      winding excavation." --Glover.
      [1913 Webster]

   3. (Engin.)
      (a) An uncovered cutting in the earth, in distinction from
          a covered cutting or tunnel.
      (b) The material dug out in making a channel or cavity.
          [1913 Webster]

                The delivery of the excavations at a distance of
                250 feet.                         --E. L.
                                                  Corthell.
          [1913 Webster]

WordNet (r) 3.0 (2006):

excavation
    n 1: the act of digging; "there's an interesting excavation
         going on near Princeton" [syn: excavation, digging,
         dig]
    2: the site of an archeological exploration; "they set up camp
       next to the dig" [syn: dig, excavation, archeological
       site]
    3: a hole in the ground made by excavating
    4: the act of extracting ores or coal etc from the earth [syn:
       mining, excavation]

Moby Thesaurus II by Grady Ward, 1.0:

153 Moby Thesaurus words for "excavation":
   abysm, abyss, arroyo, avulsion, box canyon, breach, break,
   bringing to light, burrow, canyon, casual discovery, catching,
   cavity, chance discovery, chap, chasm, check, chimney, chink,
   cleft, cleuch, clough, col, coulee, couloir, crack, cranny, crater,
   crevasse, crevice, cut, cutting out, cwm, deepening, defile, dell,
   depression, deracination, detection, determination, determining,
   dig, digging, diggings, dike, disclosure, discovery,
   disentanglement, distinguishment, ditch, donga, draw, drawing,
   drawing out, dredging, drilling, engraving, enucleation,
   eradication, espial, evolvement, evulsion, excision, exhumation,
   exposure, expression, exsection, extirpation, extraction,
   extrication, fault, find, finding, finding out, fissure, flaw,
   flume, fracture, furrow, gap, gape, gash, gorge, groove, gulch,
   gulf, gully, hole, hollow, incision, indentation, invention, joint,
   kloof, leak, locating, location, lowering, lucky strike, mine,
   mining, moat, notch, nullah, opening, pass, passage, pit,
   pressing out, probing, pulling, quarry, quarrying, ravine,
   recognition, rediscovery, removal, rent, revelation, rift, rime,
   ripping out, rupture, scissure, seam, serendipity, shaft, sinkage,
   sinking, slit, slot, split, spotting, squeezing out, strike,
   treasure trove, trench, trough, trouvaille, trove, tunnel,
   tunneling, uncovering, unearthing, unrooting, uprooting, valley,
   void, wadi, well, withdrawal, workings, wresting out