sock hat

noun2

1. •
   (US) A knitted hat, usually conical but of varying shape, often woollen, and sometimes topped by a pom-pom or tassel.

   • A red sock hat provided [the pantomime artist with] the luxurious plume of the arrogant, strutty cock, his neck bobbing, as he circulated around the farm yard. — 1969
2. •
   (US) A warm cap shielding the neck and head, often made out of wool and used in skiing, or stereotypically while committing a robbery.

   • Shuki, 31, is the only one in the picture wearing the typical woolen sock hat, which is otherwise known as a ski mask—it does get cold, and for some actions they like to cover their faces. — 2003