The phrase "occasion outfit" refers to the specific clothing someone wears for a special event or celebration. It is an outfit that is chosen specifically for that particular occasion. Full definition
You'll need to be prepared with your best special occasion outfit. (sophieandtrey.com)
For casual occasions this outfit is fabulous to wear. (adworks.pk)
It is the perfect place to pick up an excellent shoe, leather clutch bag, special occasion outfit or simply beautiful wearable pieces for everyday. (inspiringwit.com)