pho·​tom·​e·​ter fō-ˈtä-mə-tər How to pronounce photometer (audio)
: an instrument for measuring luminous intensity, luminous flux, illumination, or brightness

Examples of photometer in a Sentence

Recent Examples on the Web The network, known as AERONET, contains more than 500 sun photometer instruments that measure global aerosol optical depth. Julia Musto, Fox News, 29 June 2023 The kit also includes a Bluetooth ColorQ photometer that gives you a digital readout of your test results. Nor'adila Hepburn, Better Homes & Gardens, 1 June 2023 People would come and discuss how to build a really precise photometer. Andrew Grant, Discover Magazine, 27 Nov. 2012 So Masson's group is now developing a portable spectral photometer to augment its plasmonic tongue, thereby ensuring accurate readings. Jennifer Ouellette, Ars Technica, 28 May 2020

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'photometer.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


New Latin photometrum, from phot- + -metrum -meter

First Known Use

1779, in the meaning defined above

Time Traveler
The first known use of photometer was in 1779

Dictionary Entries Near photometer

Cite this Entry

“Photometer.” Dictionary, Merriam-Webster, Accessed 26 Sep. 2023.

Medical Definition


1 of 2 noun
pho·​tom·​e·​ter fō-ˈtäm-ət-ər How to pronounce photometer (audio)
: an instrument for measuring the intensity of light, luminous flux, illumination or brightness by comparison of two unequal lights from different sources usually by reducing the illumination of one (as by varying the distance of the source or using a polarizing device) until the two lights appear equal with the amount of adjustment serving as the basis of comparison and the equality of illumination being judged by various means


2 of 2 transitive verb
: to examine with a photometer

More from Merriam-Webster on photometer

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