etiquette, form, manners, mores, proprieties

p's and q's

amenity, civility, courtesy, decorum, politeness

air, attitude, carriage, poise, pose, posture, presence

aspect, look, mien

formality, protocol, rules

custom, habit, habitude, pattern, practice (also practise), trick, wont

convention, fashion, form, mode, style

affectation, attribute, characteristic, mark, trait

distinctiveness, oddity, peculiarity, singularity, strangeness, uniqueness, weirdness