flatcap

/ˈflætˌkæp/
noun
  1. A round, soft cap with a small brim at the front, traditionally worn by men in the UK and Ireland.
    • He bought a wool flatcap to keep his head warm during the winter.
    • The old man wore a tweed flatcap while walking his dog in the countryside.
    • In many movies, detectives and farmers are shown wearing a flatcap.