Wordnet 3.0
ADVERB (2)
1. 
 in an obligatory manner; 
- Example: "this rule applies obligatorily"2. 
 in a manner that cannot be evaded; 
- Example: "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]
The Collaborative International Dictionary of English v.0.48:
Obligatorily \Ob"li*ga*to*ri*ly\, adv.
   In an obligatory manner; by reason of obligation. --Foxe.
   [1913 Webster]
WordNet (r) 3.0 (2006):
obligatorily
    adv 1: in an obligatory manner; "this rule applies obligatorily"
           [ant: optionally]
    2: 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]