A Light

1. (physics, uncountable) Visible electromagnetic radiation. The human eye can typically detect radiation (light) in the wavelength range of about 400 to 750 nanometers. Nearby shorter and longer wavelength ranges, although not visible, are commonly called ultraviolet and infrared light.
2. A source of illumination.
3. Spiritual or mental illumination; enlightenment, useful information.
4. (in the plural, now rare) Facts; pieces of information; ideas, concepts.
5. A notable person within a specific field or discipline.
6. (painting) The manner in which the light strikes a picture; that part of a picture which represents those objects upon which the light is supposed to fall; the more illuminated part of a landscape or other scene; opposed to shade.
7. A point of view, or aspect from which a concept, person or thing is regarded.
8. A flame or something used to create fire.
9. A firework made by filling a case with a substance which burns brilliantly with a white or coloured flame.
10. A window, or space for a window in architecture.
11. The series of squares reserved for the answer to a crossword clue.
12. (informal) A cross-light in a double acrostic or triple acrostic.
13. Open view; a visible state or condition; public observation; publicity.
14. The power of perception by vision.
15. The brightness of the eye or eyes.
16. A traffic light, or, by extension, an intersection controlled by one or more that will face a traveler who is receiving instructions.*

Synonyms

• (electromagnetic wave perceived by the eye): visible light
• See also light source