To cause (an organism) to multiply or breed. To breed (offspring). To transmit (characteristics) from one generation to another. To cause to extend to a broader area or larger number; spread: missionaries who propagate the faith. To make widely known; publicize: propagate a rumor. Physics To cause (a wave, for example) to move in some direction or through a medium; transmit. To have offspring; multiply. To extend to a broader area or larger number; spread. Physics To move through a medium.