Transmittances

Part of speech: noun

Definitions

1. A measure of how much light passes through a medium, particularly in the context of optical materials
2. The fraction of incident light that is transmitted through a substance, often expressed as a percentage
3. The effectiveness of a material in allowing light to pass compared to the amount that is blocked or absorbed

Etymology: "Transmittances" is simply the plural of "transmittance," so it refers to several measurements of the fraction of light passing through different substances or samples. The singular form carries the core sense: the proportion of incident light that a material lets through, which is why it is often reported as a percentage.