Internal combustion engine
An engine in which the combustion of a fuel or fuel-air mixture takes place in an enclosed chamber, producing the power stroke directly, and in which the products of combustion form the working medium. Petrol, diesel and gas engines are internal combustion engines.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM