n. 25B6; adjective
a formal dinner : CEREMONIAL, ceremonious, ritualistic, ritual, conventional, traditional; stately, courtly, solemn, dignified; elaborate, ornate, dressy.
a very formal manner : ALOOF, reserved, remote, detached, unapproachable; stiff, prim, stuffy, staid, ceremonious, correct, proper, decorous, conventional, precise, exact, punctilious, unbending, inflexible, strait-laced; informal stand-offish.
a formal garden : SYMMETRICAL, regular, orderly, arranged, methodical, systematic.
formal permission : OFFICIAL, legal, authorized, approved, validated, certified, endorsed, documented, sanctioned, licensed, recognized, authoritative.
formal education : CONVENTIONAL, mainstream; school, institutional.
informal, casual, colloquial, unofficial.