Abbreviation for horizontal take-off and landing. A reusable hypersonic spaceplane invented by British engineer Alan Bond in 1983 but never put into production.

HOTOL was to be a single-stage vehicle that could take off and land on a runway. It featured a revolutionary dual-purpose engine that enabled it to carry far less oxygen than a conventional spaceplane: it functioned as a jet engine during the initial stage of flight, taking in oxygen from the surrounding air; when the air became too thin, it was converted into a rocket, burning oxygen from an on-board supply. The project was developed by British Aerospace and Rolls-Royce but foundered for lack of capital in 1988.