Meaning of INFORMAL in English

INFORMAL

(ˈ)in, ən+ adjective

Etymology: in- (I) + formal

1. : not formal : conducted or carried out without formal, regularly prescribed, or ceremonious procedure : unofficial

informal hearing

informal discussion

informal contract

informal inquiries

informal gathering of friends

2. : characteristic of or appropriate to ordinary, casual, or familiar use

informal English

genial, informal manner

informal essay

3. obsolete : deranged , mad

poor informal women are no more but instruments — Shakespeare

4. of a design : having an asymmetrical composition or arrangement made from unequal shapes and distances

informal balance in a stage set

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.