reproduction or multiplication, as of a plant or animal
a spreading, as of ideas, customs, etc.
See propagation in American Heritage Dictionary 4
(prŏpˌə-gāˈshən)
noun
Multiplication or increase, as by natural reproduction.
The process of spreading to a larger area or greater number; dissemination.
Physics The act or process of propagating, especially the process by which a disturbance, such as the motion of electromagnetic or sound waves, is transmitted through a medium such as air or water.