From Longman Dictionary of Contemporary Englishglad ragsglad ragsold-fashioned informal your best clothes that you wear for special occasions → glad
Examples from the Corpus
glad rags• Put on the glad rags and go out and party, after that?• She changed out of her glad rags, tugged on old jeans and a sweatshirt and drove out to his house.• Her sister-in-law's glad rags were not very glad. 