mindmap root((正式)) ceremonial, ceremonious both imply strict attention to what is prescribed by custom or by ritual, but ceremonial applies to things that are associated with ceremonies: a ~ offering; ceremonious to persons given to ceremony or to acts attended by ceremony: a ~ old man. formal applies both to things prescribed by and to persons obedient to custom and may suggest stiff, restrained, or old-fashioned behavior: a ~ report on the summit meeting; a ~ manner. conventional implies accord with general custom and usage and may suggest a lack of originality or independence: ~ courtesy; ~ standards of beauty.