Search Result for "reaction propulsion":
Wordnet 3.0

NOUN (1)

1. propulsion that results from the ejection at high velocity of a mass of gas to which the vehicle reacts with an equal and opposite momentum; 



WordNet (r) 3.0 (2006):

reaction propulsion
    n 1: propulsion that results from the ejection at high velocity
         of a mass of gas to which the vehicle reacts with an equal
         and opposite momentum