**Dyne** (*dīn*)**,** the unit of force employed in the metric system. It is defined as that force which, acting upon a mass of one gram, will produce unit-acceleration. If we denote the acceleration of gravity by *g*, then the weight of one gram is equal to *g* dynes. And, in general, we may say that the weight, W, of any body whose mass is *m* grams is *mg* dynes, or

*mg*dynes.

A definition of the dyne which is exactly equivalent to that given above is the following: That force which, acting for one second, will produce unit-change of velocity in a mass of one gram. A *megadyne* is a force of one million dynes, and is about two *per cent.* greater than the weight of a kilogram.