semidiesel engine

\\“+-\ noun

: an internal-combustion engine usually of the two-stroke cycle type and below 50 horsepower that resembles a diesel engine:

a. : an internal-combustion engine of a type resembling the diesel engine in using heavy oil as fuel but employing a lower compression pressure of 100 to 350 pounds per square inch and igniting the charge by spraying it under pressure against an uncooled portion of the combustion chamber, by spraying it into a separate chamber kept above the ignition temperature of the charge by the heat of compression, or by the preignition or supercompression of a portion of the charge in a separate member or uncooled portion of the combustion chamber

b. : a true diesel engine using other means of fuel injections than compressed air

c. : a mixed-cycle engine closely resembling a diesel engine