regulation cap; school cap
flat cap; cloth cap; newsboy cap; (hunting) cap
red cap; (railway) porter; redcap
mitral valve; bicuspid valve
three-cornered hat; tricorne
mortarboard; trencher; (square) academic cap formerly worn by Japanese university students
aviation cap; flying helmet
field cap (used by Japanese troops in WWII)
safety helmet; crash helmet; hard hat
hat worn by kindergarten or primary school pupils walking to school
shabby clothes and an old hat
red and white reversible cap