from the GNU version of the Collaborative International Dictionary of English
- adj. See under Pressure.
- n. pressure which resists the motion of the piston, as the pressure of exhaust steam which does not find free outlet.
from The Century Dictionary and Cyclopedia
- n. Pressure backward or in the reverse of the normal direction; specifically, the resistance of the atmosphere or of waste steam to the action of the piston of a steam-engine.
Sorry, no etymologies found.