Wordnet 3.0
ADVERB (2)
1. 
 in a servile manner; 
- Example: "he always acts so deferentially around his supervisor"[syn: deferentially, submissively]
2.  in a respectfully deferential manner; 
- Example: "he listened deferentially"
The Collaborative International Dictionary of English v.0.48:
Deferentially \Def`er*en"tial*ly\, adv.
   With deference.
   [1913 Webster]
WordNet (r) 3.0 (2006):
deferentially
    adv 1: in a servile manner; "he always acts so deferentially
           around his supervisor" [syn: deferentially,
           submissively]
    2: in a respectfully deferential manner; "he listened
       deferentially"