What is "cocktail hat"

n. A type of small, extravagant women's hat, such as a fascinator, suitable as evening wear or for cocktail parties.

A cocktail hat is a small, extravagant hat for a woman. It is usually a component of evening wear and is intended as an alternative to a large-brimmed hat. These hats are often decorated with beads, jewels or feathers, as well as a veil. They are closely related to fascinators, which are extravagant hairpieces worn on the side of the head.