compression stroke

Definitions

General Science

  • noun the stage of an internal combustion cycle when the fuel–air mixture comes under pressure from the upwards-moving piston

Cars & Driving

  • noun an upward stroke of the piston with both valves closed; as the piston ascends, the air/fuel mixture (in diesel engines air only) is compressed, increasing pressure and temperature of the charge before ignition
http://www.dictionarycentral.com/definition/compression-stroke.html