You searched for: “costume
costume, custom
costume (KAHS toom", KAHS tyoom") (noun)
An article, or articles, of clothing: The costume that the actor wore had been made of gold cloth.
custom (KUS tuhm) (noun)
1. A long established practice: It was the family custom to go for a walk in the woods before dinner.
2. A duty or tax on imported and some exported goods: Kurt was informed at the border that he could not bring the package into the country until he paid the officer the required custom.

It is the custom at New Years to wear an elaborate costume to parties.