Boot

A boot was a type of clothing worn on one's foot. They were part of a regulation Starfleet uniform.

Captain Nick Keller habitually wore cowboy boots while on duty. 

Mark McHenry once put on a sock over his boot. 

Ensign Mayer once lost his boot and didn't realize it until he broke his foot running into a console. (SS DS9 (Mirror Eyes))

Ilirra Deel once wore thigh-high boots as part of a disguise.