specific impulse

noun Rocketry.

a measure, usually in seconds, of the efficiency with which a rocket engine utilizes its propellants, equal to the number of pounds of thrust produced per pound of propellant burned per second.
the specific impulse that a given combination of propellants would produce in an ideal rocket engine providing complete combustion, no friction losses, and no lateral expansion of the exhaust.

Origin of specific impulse

First recorded in 1945–50
Also called specific thrust.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for specific impulse

specific impulse


the ratio of the thrust produced by a rocket engine to the rate of fuel consumption: it has units of time and is the length of time that unit weight of propellant would last if used to produce one unit of thrust continuously
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012