thumbnail

from WordNet (r) 3.0 (2006)

thumbnail
    n 1: the nail of the thumb

from The Free On-line Dictionary of Computing (8 July 2008)

thumbnail
thn

   <file format, graphics> (From "thumbnail sketch") A file
   format used by {Graphics Workshop} for {Microsoft Windows}.
   {Filename extension}: ".thn".

   [What's in the files?]

   (1996-05-28)