"informally" in the adverb sense
1. informally
without formality
"he visited us informally"
2. colloquially, conversationally, informally
with the use of colloquial expressions
"this building is colloquially referred to as The Barn"
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License