Albedos

Part of speech: noun

Definitions

1. The measurement that represents the fraction of incident light reflected by a surface indicates its reflective power
2. A ratio expressing the amount of light or radiation that surfaces reflect compared to what they receive
3. The proportion of incoming light energy that is bounced back by an object or material instead of being absorbed

Etymology: "Albedos" is simply the plural of "albedo," so it names several such measurements at once. The noun "albedo" is the English form of the Latin "albēdō," meaning "whiteness," which is built from "albus," meaning "white." The Latin base connects it to a long line of words for pale colour, and the suffix "-ēdō" marks a state or quality, much like "whiteness" itself does in English. English borrowed the term from Latin with its original sense of whiteness intact. Over time it narrowed to a precise measurement: the fraction of incoming light that a surface or body reflects back. A fresh snowfield has a high albedo, while dark asphalt has a low one, so the word that once described colour now quantifies how bright something is to the eye of a planet or a camera.