(idiomatic) Very fancily or formally dressed; wearing very showy or splendid clothing.

The dance costume prescribed for females performing the Scottish National dances in competitions at Highland games gatherings. It consists of a dark bodice or elaborate waistcoat, decorative blouse, full tartan skirt and sometimes a petticoat and apron, or a tartan sash.

A rehearsal prior to a public spectacle, where all the performers are in costume, in order to test all aspects of the production by closely reproducing the actual conditions of a performance.

(intransitive) To put on special or fancy clothes. / (intransitive, often with 'as') To put on a costume portraying oneself as a particular type of character or well-known person.

Any treatment of an ore used to concentrate its valuable constituents (minerals) into products (concentrate) of smaller bulk, and simultaneously to collect the worthless material (gangue) into discardable waste (tailings).

the clothing worn by a female tennis player

A block of silicon carbide or aluminium oxide used to dress diamond tools by removing the build-up of metal etc.

(now historical) A woman's dress designed for informal day wear.

To decorate the window of a shop / To give something superficial attractiveness

(idiomatic) A reprimand or rarely, a thrashing.