The Collaborative International Dictionary of English v.0.48:

Unearth \Un*earth"\, v. t. [imp. & p. p. Unearthed; p. pr. &
   vb. n. Unearthing.] [1st pref. un- + earth.]
   To drive or draw from the earth; hence, to uncover; to bring
   out from concealment; to bring to light; to disclose; as, to
   unearth a secret.
   [1913 Webster]

         To unearth the roof of an old tree.      --Wordsworth.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unearth
    v 1: bring to light; "The CIA unearthed a plot to kill the
         President"
    2: recover through digging; "Schliemann excavated Troy";
       "excavate gold" [syn: excavate, unearth]

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "unearth":
   ascertain, avulse, bring to light, catch on, come across, cut out,
   delve, deracinate, determine, dig, dig out, dig up, disclose,
   discover, disentangle, disinter, draw, draw out, dredge, dredge up,
   eradicate, evolve, evulse, excavate, excise, exhibit, exhume,
   expose, exsect, extract, extricate, ferret out, find, find out,
   fish up, get out, gouge out, grub up, hear, learn, mine, pick out,
   pluck out, pluck up, pull, pull out, pull up, quarry, rake out,
   remove, reveal, rip out, root out, root up, see, show, take out,
   tear out, tumble, turn up, uncover, unravel, uproot, weed out,
   withdraw, worm out, wrest out