The Collaborative International Dictionary of English v.0.48:

Compulsorily \Com*pul"so*ri*ly\, adv.
   In a compulsory manner; by force or constraint.
   [1913 Webster]

WordNet (r) 3.0 (2006):

compulsorily
    adv 1: in a manner that cannot be evaded; "the ministry
           considers that contributions to such a fund should be met
           from voluntary donations rather than from rates
           compulsorily levied." [syn: compulsorily,
           obligatorily, mandatorily]