Luminous

Luminous is an English adjective describing something that emits, reflects, or is intensely illuminated by light. The term derives from Latin lumen, meaning light, and the suffix -ous. In everyday usage, luminous objects are bright or radiant. In scientific contexts, luminous describes phenomena associated with light emission, including both visible and near-visible spectra.

In physics and photometry, luminous intensity is measured in candelas, luminous flux in lumens, and luminance in nits. Illuminance, measured in lux, describes how much light falls on a surface, while luminous efficiency relates luminous flux to radiant power. The study of how materials emit light collectively falls under luminescence, with subtypes such as fluorescence (prompt emission) and phosphorescence (delayed emission). Bioluminescence occurs in living organisms, chemiluminescence arises from chemical reactions, and radioluminescence from radioactive excitation.

In culture, the word luminous is often used to evoke brightness, clarity, or emotional radiance and appears as a title or motif in literature, film, and music. It is also used commercially to describe lighting products and materials that glow or emit light. Brands such as Luminous Power Technologies produce power backup equipment, including batteries and inverters, and glow-in-the-dark or photoluminescent materials are commonly labeled as luminous.

See also luminescence, luminosity, lumen.