informal

from WordNet (r) 3.0 (2006)
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:
       {informal}, {loose}]
    3: used of spoken and written language [ant: {formal}]
    4: 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" [syn: {cozy}, {intimate}, {informal}]
    
from The Collaborative International Dictionary of English v.0.48
Informal \In*form"al\, a. [Pref. in- not + formal.]
   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.
      [1913 Webster]

   2. Deranged in mind; out of one's senses. [Obs.]
      [1913 Webster]

            These poor informal women.            --Shak.
      [1913 Webster]
    
from Moby Thesaurus II by Grady Ward, 1.0
108 Moby Thesaurus words for "informal":
      Bohemian, affable, beat, beat-up, bedraggled, blowzy, breakaway,
      careless, casual, chintzy, colloquial, common, conversational,
      cordial, degage, dilapidated, drabbletailed, draggled,
      draggletailed, easy, easygoing, en deshabille, everyday, familiar,
      far out, folksy, free, free and easy, fringy, frowzy, frumpish,
      frumpy, garden-variety, gracious, grubby, haymish, heretical,
      heterodox, hippie, homely, homey, in dishabille, in rags,
      irregular, kinky, loose, lumpen, maverick, messy, mussy, natural,
      negligent, nonstandard, not cricket, not done, not kosher, offbeat,
      offhand, offhanded, ordinary, original, plain, poky, private,
      ragged, raggedy, relaxed, ruinous, scraggly, seedy, shabby, shoddy,
      simple, slack, slatternly, slipshod, sloppy, slovenly, sluttish,
      sociable, sordid, special, spoken, spontaneous, sporty, squalid,
      substandard, tacky, tattered, unaffected, unassuming, unauthorized,
      unceremonious, unconstrained, unconventional, uneducated,
      unfashionable, unkempt, unliterary, unneat, unofficial, unorthodox,
      unpretentious, unsightly, unstudied, untidy, vernacular, way out

    

[email protected]