transmittance vs transmission

transmittance and transmission both are nouns.

Word	Noun	Adjective	Verb	Adverb
transmittance	Yes	No	No	No
transmission	Yes	No	No	No

As nouns, transmittance and transmission are synonyms defined as:

transmittance and transmission: the fraction of radiant energy that passes through a substance

transmittance (noun)	transmission (noun)
the fraction of radiant energy that passes through a substance	the act of sending a message; causing a message to be transmitted
	the gears that transmit power from an automobile engine via the driveshaft to the live axle
	communication by means of transmitted signals
	an incident in which an infectious disease is transmitted
	the fraction of radiant energy that passes through a substance