Reflectances

Part of speech: noun

Definitions

1. The quality of reflecting light or other electromagnetic waves in varied intensities; the degree to which a surface reflects light rather than absorbing it; a measure of the amount of light that bounces off an object, influencing visibility and color perception
2. The characteristic of a material indicating how efficiently it can send back light or other forms of radiation; the ratio of reflected light to the incident light on a surface, which is important in optics and photography; an important property in determining the brightness and appearance of surfaces under various lighting conditions
3. The extent to which a surface can reflect light or other forms of energy, calculated as a fraction of the incident energy; an essential property for surfaces in many applications including environmental science and material studies; a key factor that affects how objects are perceived visually in terms of color and brightness

Etymology: "Reflectances" is simply the plural of "reflectance," which is formed from the verb "reflect" plus the suffix "-ance." The suffix traces back through Old French "-ance" to Latin "-antia," a pattern that gave English many abstract nouns of quality and state, such as "importance" and "abundance." Attaching it to "reflect" produces a noun for the condition or degree of reflecting, which in physics and optics is the proportion of light or other radiation that a surface bounces back. The plural form is used when speaking of several such measurements or surfaces at once, as when comparing the reflectances of different materials, paints, or ground types. Because the base word is a verb, the noun carries the sense of an action turned into a measurable property, which is why it reads more like a quantity than a quality.