The Collaborative International Dictionary of English v.0.48:

Inundate \In*un"date\, v. t. [imp. & p. p. Inundated; p. pr. &
   vb. n. Inundating.] [L. inundatus, p. p. of inundare to
   inundate; pref. in- in + undare to rise in waves, to
   overflow, fr. unda a wave. See Undulate.]
   [1913 Webster]
   1. To cover with a flood; to overflow; to deluge; to flood;
      as, the river inundated the town.
      [1913 Webster]

   2. To fill with an overflowing abundance or superfluity; as,
      the country was inundated with bills of credit.

   Syn: To overflow; deluge; flood; overwhelm; submerge; drown.
        [1913 Webster]

WordNet (r) 3.0 (2006):

inundate
    v 1: fill quickly beyond capacity; as with a liquid; "the
         basement was inundated after the storm"; "The images
         flooded his mind" [syn: deluge, flood, inundate,
         swamp]
    2: fill or cover completely, usually with water [syn:
       inundate, deluge, submerge]

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "inundate":
   afflict, aggrieve, anguish, baptize, be prodigal with, board,
   break down, bring to tears, bury, cascade, cataract, crush, cut up,
   deluge, desolate, dip, douse, draw tears, drown, duck, dunk,
   embitter, engulf, escalade, float, flood, flood the market,
   flow on, foray, grieve, hit and run, immerge, immerse, inroad,
   invade, make a raid, make an inroad, merge, oppress, overbrim,
   overdose, overequip, overflow, overfurnish, overlavish,
   overprovender, overprovide, overprovision, override, overrun,
   oversell, overstock, oversupply, overwhelm, plunge in water,
   pour on, pour out, pour over, prostrate, raid, rain, ride down,
   ride over, ride roughshod over, run down, run over, scale,
   scale the walls, sink, slop, slosh, sluice, sorrow, souse, spill,
   spill out, spill over, storm, submerge, submerse, swamp, sweep,
   take by storm, torment, trample, trample on, trample underfoot,
   trample upon, tread upon, whelm