Toothbrush moustache
A short, square block of moustache under the nose, with the sides shaved.
Also: toothbrush
The toothbrush moustache is a narrow rectangle of hair, as wide as the nose or a little wider, trimmed short. It was popular in the United States and Europe from the late nineteenth century as a tidy alternative to large styles, and Charlie Chaplin wore one on screen. After the Second World War its association with Adolf Hitler made it rare, and it is now seldom worn.