il·​lu·​mi·​nant i-ˈlü-mə-nənt How to pronounce illuminant (audio)
: an illuminating device or substance

Example Sentences

at the time, a spermaceti candle was the brightest indoor illuminant available
Recent Examples on the Web Distilling rock oil produced multiple interesting compounds, one of which looked like an ideal illuminant. Charles R. Morris, WSJ, 21 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'illuminant.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

First Known Use

1644, in the meaning defined above

Time Traveler
The first known use of illuminant was in 1644

Dictionary Entries Near illuminant

Cite this Entry

“Illuminant.” Dictionary, Merriam-Webster, Accessed 2 Feb. 2023.

Medical Definition


il·​lu·​mi·​nant -nənt How to pronounce illuminant (audio)
: an illuminating device or substance (as for a microscope)
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