What is the X in X-mas?  ion propulsion  Rocketry. a projected
type of propulsion for vehicles in outer space, the exhaust
consisting of positive ions and negative electrons repelled from
the vehicle by electrostatic forces, resulting in a very high
exhaust velocity. Also, ionic propulsion. Unabridged Cite This
Source Examples from the web for ion propulsion   • Install an
ion propulsion engine and send it slowly to its destination.
Word of the Day  Difficulty index for ion propulsion  Few
English speakers likely know this word  Word Value for ion
Scrabble Words With Friends  Nearby words for ion propulsion