Wellington boot

Century Dictionary and Cyclopedia

1. n. A riding-boot with leg extending upward at the rear to the angle of the knee, and high enough in front to cover the knee. So called because the pattern is supposed to have been introduced by the Duke of Wellington, who wore such boots in his campaigns.
2. n. A similar boot, somewhat shorter, worn under the trousers, and fitting the leg closely.

Wiktionary

1. n. One of a pair of Wellington boots.

GNU Webster's 1913

1. A riding boot for men, the front of which came above the knee; also, a similar shorter boot worn under the trousers.

WordNet 3.0

1. n. (19th century) a man's high tasseled boot