-ishən noun
( -s )
Usage: often attributive
Etymology: Latin transmission-, transmissio, from transmissus (past participle of transmittere to transmit) + -ion-, -io -ion
1. : an act, process, or instance of transmitting: as
a. : the overall proportion of radiant energy homogeneous with respect to wavelength that is transmitted perpendicularly through a substance bounded by plane nondiffusing parallel surfaces (as a plate of glass or other homogeneous isotropic nondiffusing medium or series of such media in contact with one another) and that is the ratio of the amount of energy emerging from the last surface to the amount incident upon the first with the difference between the two amounts resulting from losses of radiant energy due to reflection at the surfaces and absorptance and scattering within the medium — called also attenuation factor ; compare transmittance 2
b. : the passage of radio waves in the space between transmitting and receiving stations ; also : the act or process of transmitting by radio or television
2. : the gear including the change gear and the propeller shaft or driving chain by which power is transmitted from the engine of an automobile to the live axle — called also gearbox ; see selective transmission
3. : the train of a watch
4. : something that is transmitted : message
the machine records telegraphic transmissions