definition of
informal

[1] #1 informal a. not formal; "conservative people unaccustomed to informal dress"; "an informal free-and-easy manner"; "an informal gathering of friends". wn

[2] #2 informal a. used of spoken and written language. wn

[3] #3 informal s. [cozy, intimate] having or fostering a warm or friendly and informal atmosphere; "had a cozy chat"; "a relaxed informal manner"; "an intimate cocktail lounge"; "the small room was cozy and intimate". wn