What is the name of a round, flat hat with a brim, often made of straw?

A round, flat hat with a brim, often made of straw, is called a boater hat. It typically has a stiff, flat crown and a straight, horizontal brim, with a ribbon or band wrapped around the crown. The structured shape distinguishes it from softer felt hats such as the fedora or trilby.

Boater hats became associated with boating, rowing, sailing, and warm-weather leisure during the late 19th and early 20th centuries. Their rigid straw construction provided shade while holding its shape in wind and outdoor settings. The hat also became part of formal summer dress, school uniforms, and theatrical or musical performance costumes.

The boater is sometimes confused with a Panama hat because both are commonly made from straw. A Panama hat, however, is defined by its traditional construction from toquilla straw and usually has a flexible, shaped crown. A fedora has a pinched crown and creased top, while a trilby generally has a narrower brim and a more sharply angled profile.

Boater hats are also known as sailor hats or skimmers in some contexts. Their clean geometry and association with Edwardian and early-20th-century dress have kept them recognizable in fashion, period costume, and events such as rowing regattas.