unreflected

Unreflected is an adjective with two primary uses. In physics and optics, it describes light or other radiation that is not reflected by a surface; in cognitive or general usage, it describes ideas or actions that have not undergone consideration or contemplation.

In optics, unreflected light is energy that does not bounce off a boundary. The portion that is reflected is called the reflectance; the remainder is transmitted or absorbed. Surfaces may be designed to minimize unreflected light with anti-reflective coatings, or to maximize reflection for mirror-like finishes. In measurements, researchers often report reflectance (R), transmittance (T), and absorption (A), with R + T + A = 1 for a single wavelength and a given geometry.

In non-physical usage, unreflected can describe a decision, action, or thought that has not been considered. It is less common than unreflective or thoughtless, and can carry a critical nuance when applied to judgments or conclusions.

Etymology and usage notes: The word derives from un- + reflected, from Latin reflectere. It appears in English from the early modern period but remains relatively rare outside technical contexts. Related terms include reflect, reflection, reflective, and unreflective.