Antonyms for formal

all:

informal.

austere:

calm, gentle, bland, mild, meek.

chill:

responsive, warm, sympathetic, friendly.

civil:

impolite, unkind, rude, ill-mannered.

conventional:

abnormal, uncustomary, strange, unusual, uncommon, foreign, unconventional, exotic, irregular.

courtly:

unpolished, low-bred, rough, unrefined, uncivil, provincial, inelegant, indecorous.

decorous:

indecent, unbecoming, unfit, inappropriate, unsuitable, unseemly.

dignified:

undignified, dishonorable.

established, orderly:

inaccurate, ordinary, indefinite, ambiguous.

formal:

disorderly, informal, normal, customary, unaffected, relaxed.

noun:

freewheeling, unfashionable, inappropriate, mussy, rough, untidy, indecent, discourteous, unrefined, lowbred, wrinkled, sloven, sloppy, improper, unkempt, rumpled, street, real, indecorous, unfit, slovenly, Ineloquent, representational, infelicitous, gross, unlogical, unseemly, ungrammatical, unauthorized, Unapt, coarse, disheveled, low, lowbrow, true, crude, unpolished, unbecoming, impolite, rude, graceless, uneducated, unsuitable, styleless, messy, sporty, frowsy, unmannerly, dowdy, unstylish, uncultivated, ill-bred, unhappy, outmoded, inept, uncouth, incorrect, actual, grungy, illogical, substandard, tasteless, unlearned, uncultured, crass.