The Collaborative International Dictionary of English v.0.48:

Tenfold \Ten"fold`\, a. & adv.
   In tens; consisting of ten in one; ten times repeated.
   [1913 Webster]

         The grisly Terror . . . grew tenfold
         More dreadful and deform.                --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ten-fold
    adj 1: containing ten or ten parts [syn: tenfold, ten-fold,
           denary]