pho·tom·e·ter | \fō-ˈtä-mə-tər \

Definition of photometer 

: an instrument for measuring luminous intensity, luminous flux, illumination, or brightness

First Known Use of photometer

1779, in the meaning defined above

History and Etymology for photometer

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

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The first known use of photometer was in 1779

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pho·tom·e·ter | \fō-ˈtäm-ət-ər \

Medical Definition of photometer 

(Entry 1 of 2)

: 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


transitive verb

Medical Definition of photometer (Entry 2 of 2)

: to examine with a photometer

More from Merriam-Webster on photometer

See words that rhyme with photometer Encyclopedia article about photometer

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