Wordnet 3.0
ADVERB (2)
1. 
 without formality; 
- Example: "he visited us informally"2. 
 with the use of colloquial expressions; 
- Example: "this building is colloquially referred to as The Barn"[syn: colloquially, conversationally, informally]
The Collaborative International Dictionary of English v.0.48:
Informally \In*form"al*ly\, adv.
   In an informal manner.
   [1913 Webster]
WordNet (r) 3.0 (2006):
informally
    adv 1: without formality; "he visited us informally" [ant:
           formally]
    2: with the use of colloquial expressions; "this building is
       colloquially referred to as The Barn" [syn: colloquially,
       conversationally, informally]