The Collaborative International Dictionary of English v.0.48:

Insomuch \In`so*much"\, adv.
   So; to such a degree; in such wise; -- followed by that or
   as, and formerly sometimes by both. Cf. Inasmuch.
   [1913 Webster]

         Insomusch as that field is called . . . Aceldama.
                                                  --Acts i. 19.
   [1913 Webster]

         Simonides was an excellent poet, insomuch that he made
         his fortune by it.                       --L'Estrange.
   [1913 Webster]

WordNet (r) 3.0 (2006):

insomuch
    adv 1: to such an extent or degree; so