What is "platform boot"

n. A fashionable boot with very thick soles and heels to make the wearer appear taller.

Platform boots are boots with thick wedge soles or a combination of thick soles and high heels that are similar in some respects to the platform shoe. They were seen as the cutting edge of fashion in the United Kingdom during the 1970s and during the British invasion. They were worn by both men and women.