Synonyms for Formal:

adj.

austere (adjective)
stiff.
civil (adjective)
mannerly, courtly.
courteous (adjective)
polite.
courtly (adjective)
elegant, dignified.
decorous (adjective)
conforming.
formal (adjective)
prescribed, ritual, official, academic, approved, stilted, ritualistic, proper, ceremonious, stately, directed, lawful, confirmed, legal, distant, set, precise, ceremonial, regular, nominal, conventional, polite, punctilious, reserved, pro forma.
ostentatious (adjective)
pompous, affected, flourishing, garish, snazzy, dramatic, Flaunting, exhibitionistic, gaudy, grandiose, grandiloquent, sensational, histrionic, ornate, jaunty, vain, opulent, stilted, flashy, boastful, dashing, rakish, forced, shameless, showy, fussy, flamboyant, blatant, splashy, ostentatious, flagrant.
restrained (adjective)
reserved.

n.

backless, button-down, boot-cut, brief, A-LINE, set, best, button-through, Clingy, casual, symmetrical, precise, baggy, orderly. accessible, abstract, artsy-craftsy, polite, aesthetic, reserved, campy, avant-garde, baroque, distant, camp, artistic. advanced, academic, diachronic, graduate, applied, social, educational, didactic, dressed-up, elementary, dressy, curricular. punctilious, aerate, deadhead, bed out, cross-fertilize, drill, compost, courtesy, cross-pollinate, feed, bonsai. discursive, crisp, economical, ritualistic, clean, diffuse, liturgical, declamatory, articulate, chatty, ritual, conversational, circuitous. gown, cocktail dress, dirndl, ballgown, frock, evening dress, cheongsam, chemise. folk dance, ballroom dancing, cheerleading, tap dancing, belly dancing, body popping, tap, breakdancing, line dancing. mechanised, bottom-up, thus, through, head-on, top-down, mechanized, whereby, Via. dance (noun)
social.
formal (noun)
nominal, ceremonious, dress, buckram, elegant, black tie, courtly, form-only, stately, full dress, perfunctory, dignified, positive, titular, white tie, logical, starchy, semiformal, semi-formal, ceremonial, conventional, stiff, official, literary, nonrepresentational, schematic, prescribed, pro forma.
official (noun)
lawful, approved, legal, confirmed, directed.

Other synonyms:

whereby, body popping, cheongsam, tap dancing, folk dance, dirndl, mechanized, diachronic, triumphal, ballgown, applied, BYOB, ballroom dancing, bacchanalian, breakdancing, didactic, dressed-up, bottom-up, elementary, cocktail dress, educational, line dancing, Via, curricular. advanced, academic, graduate, top-down, evening dress, cheerleading, ritualistic, head-on, liturgical, thus, orderly, frock. punctilious. ritual, gown. tap. through. black-tie
black tie.
eloquent
declamatory.
formal
dressy.
full-dress
full dress.
stiff
stiff.
white-tie
white tie.

Usage examples for formal

  1. I'm introduced reg'lar and formal and Mr. Robert adds: " A young friend of mine from the office." – Torchy, Private Sec. by Sewell Ford
  2. A man born in Virginia could return to the Old World for training or formal education and then practice in Virginia. – Medicine in Virginia, 1607-1699 by Thomas P. Hughes