thumbprint

thumbprint
    n 1: fingerprint made by the thumb (especially by the pad of the
         thumb)
    

40 Moby Thesaurus words for "thumbprint":
      boss, bump, colophon, concavity, convexity, dactylogram,
      dactylograph, dent, dint, embossment, excrescence, fingerprint,
      footmark, footprint, footstep, fossil footprint, ichnite,
      ichnolite, impress, impression, imprint, indent, indentation,
      indention, lump, pad, paw print, pawmark, pimple, print, pug,
      pugmark, seal, sigil, signet, stamp, step, stud, thumbmark,
      vestige