1. Having or involving a pressure greatly exceeding that of the atmosphere; said of steam, air, water, etc, and of steam, air, or hydraulic engines, water wheels, etc.
2. Urgent; intense; as, a high-pressure business or social life. High-pressure engine, an engine in which steam at high pressure is used. It may be either a condensing or a noncondensing engine. Formerly the term was used only of the latter. See steam engine.