Webster: Beret (noun), 1. A cap with no brim or bill; made of soft cloth.
Origin: French, 'Basque Cap', from Latin birrus 'hooded cape'.
Basque Encyclopedic Dictionary of Auñamendi: the beret is a cap without visor, round and flattened, of wool and consists of one single piece.
Boinas Elosegui: Clothing accessory made of wool with the shape of a hemispherical skullcap for the purpose of covering the head as simply as possible.