Added 9 October 2026 transmittance noun Categories: Describing WordsRare Words noun ! Definition from Wiktionary (CC BY-SA). More about transmittance at Wordnik → Where our words come from → A transmission. The fraction of incident light, or other radiation, that passes through a substance. Related Words: transmissiontransmittingtransmittransmittedtransmittalforwardingtransfertrannyconveyingtranstransceptiontran Back to today's word