informally

from 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}]

from The Collaborative International Dictionary of English v.0.48

Informally \In*form"al*ly\, adv.
   In an informal manner.
   [1913 Webster]