Origin: Latin suffix -tion
Illumination has 6 different meanings across 1 category:
the degree of visibility of your environment
"The sudden flicker of the streetlights reduced the illumination, making it difficult to see where I was walking."
an interpretation that removes obstacles to understanding
"the professor's clarification helped her to understand the textbook"
the luminous flux incident on a unit area
"The photometric measurement showed that the illumination at the workbench was insufficient for detailed assembly tasks."
painting or drawing included in a book (especially in illuminated medieval manuscripts)
"The rare manuscript was treasured not just for its text, but for the vibrant gold leaf illumination adorning each page."
The act of illuminating, or supplying with light; the state of being illuminated.
"The sudden illumination from the streetlamp allowed him to see the path clearly in the darkness."
In plain English: Illumination is light that makes something visible.
"The streetlamp provided enough illumination to walk safely home at night."
Usage: Use "illumination" to refer to the general provision of light or a specific decorative display, such as holiday lights, rather than describing the brightness itself. Avoid using it casually for simple lighting needs where "lighting" is more direct and natural.
The word entered English via the path of borrowing from Middle French and then Late Latin. It originally referred to the act or process of lighting something up with light.