English Reference
noun

illumination

n.
US /ˌɪˌɫuməˈneɪʃən/ UK /ɪlˌuːmɪnˈeɪʃən/ il·lu·mi·na·tion UK spelling illuminations

  1. 01 B2 Upper Intermediate Formal

    the light that comes from a source, or the act of lighting up a place.

    the act of supplying with light or the state of being illuminated by a source.

    Simple

    The street lamps provided just enough illumination to see the path ahead.

    In context

    The architect relied on natural illumination from the skylights to reduce the building's dependence on electrical systems during the day.

    Usage

    Uncountable when referring to the state of being lit; countable when referring to a specific source of light.

  2. 02 C1 Advanced AcademicFormal

    the act of making something clear or easy to understand.

    the process of making something clear or providing intellectual or spiritual enlightenment.

    Simple

    The lecture provided some illumination on the complex causes of the war.

    In context

    The philosopher sought spiritual illumination through years of silent meditation and rigorous study of ancient texts.

    Usage

    Usually uncountable in this figurative sense.

  3. 03 C2 Proficiency TechnicalLiterary

    the gold, silver, or bright colours used to decorate old handwritten books.

    the decoration of manuscripts or books with coloured illustrations, gold, or silver.

    Simple

    The medieval Bible was famous for its beautiful gold illumination.

    In context

    Scholars examined the intricate illumination in the margins of the fourteenth-century manuscript to identify the specific workshop that produced it.

The effect also occurred at illumination levels similar to those found indoors or outside on an overcast day.

ScienceDaily· 28 Aug 2026

Rounding out the controls are a power button and a button for the lights (which can switch between two angles of forward illumination, the higher one making you more visible to cars).

Ars Technica· 5 Aug 2026

Borrowed from Middle French illumination, from Late Latin illuminatio, from Latin illumino. Equivalent to illuminate + -ion.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Latin illumino
Level B2 · Upper Intermediate
Frequency Frequent
Updated