The Collaborative International Dictionary of English v.0.48:

Formally \Form"al*ly\, adv.
   In a formal manner; essentially; characteristically;
   expressly; regularly; ceremoniously; precisely.
   [1913 Webster]

         That which formally makes this [charity] a Christian
         grace, is the spring from which it flows. --Smalridge.
   [1913 Webster]

         You and your followers do stand formally divided
         against the authorized guides of the church and rest of
         the people.                              --Hooker.
   [1913 Webster]

WordNet (r) 3.0 (2006):

formally
    adv 1: with official authorization; "the club will be formally
           recognized" [syn: formally, officially]
    2: in a formal manner; "he was dressed rather formally" [ant:
       informally]