in·for·mal /(ˌ)ɪnˈfɔrməl/
  (a.)非正式的,不拘禮的,通俗的
  informal
  非型式 非正式
  In·form·al a.
  1. Not in the regular, usual, or established form; not according to official, conventional, prescribed, or customary forms or rules; irregular; hence, without ceremony; as, an informal writing, proceeding, or visit.
  2. Deranged in mind; out of one's senses. [Obs.]
     These poor informal women.   --Shak.
  ◄ ►
  informal
       adj 1: not formal; "conservative people unaccustomed to informal
              dress"; "an informal free-and-easy manner"; "an
              informal gathering of friends" [ant: formal]
       2: not officially recognized or controlled; "an informal
          agreement"; "a loose organization of the local farmers"
          [syn: loose]
       3: used of spoken and written language [ant: formal]
       4: having or fostering a warm or friendly atmosphere;
          especially through smallness and informality; "had a cozy
          chat"; "a relaxed informal manner"; "an intimate cocktail
          lounge"; "the small room was cozy and intimate" [syn: cozy,
           intimate]