noun
Meaning 1
The luminous flux incident on unit area of a surface; commonly measured in lux (lumen/metre2) or otherwise foot-candles. The illuminance of a star upon the earth is frequently measured on a negative logarithmic scale referred to as its apparent magnitude, which see.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Topics: natural-sciences, physical-sciences, physics
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided