transmittancy

noun

physics a measure of the extent to which a solution transmits radiation. It is equal to the ratio of the transmittance of the solution to the transmittance of a pure solvent of the same dimensions

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012