• synonyms


See more synonyms for actinometer on Thesaurus.com
  1. a device for measuring intensity of radiation, especially that of the sun.
Show More
Compare actinograph.

Origin of actinometer

First recorded in 1825–35; actino- + -meter
Related formsac·tin·o·met·ric [ak-tin-oh-me-trik, ak-tuh-noh-] /ækˌtɪn oʊˈmɛ trɪk, ˌæk tə noʊ-/, ac·tin·o·met·ri·cal, adjectiveac·ti·nom·e·try, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words


Examples from the Web for actinometer

Historical Examples

  • A Johnson's actinometer is very useful to time the exposure.


    Henry R. Blaney

  • We can, however, by chemical means arrive at an exact estimate of the active power, and for this purpose an actinometer is used.

  • You may sometimes find that the actinometer indicates a very different exposure from what the eye would lead you to expect.

  • The actinometer indicated an exposure of thirty seconds where in good light one would be right.

  • For judging long exposures, the use of an actinometer (issued in many inexpensive forms) is helpful.

British Dictionary definitions for actinometer


  1. an instrument for measuring the intensity of radiation, esp of the sun's rays
Show More
Derived Formsactinometric (ˌæktɪnəʊˈmɛtrɪk) or actinometrical, adjectiveactinometry, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

actinometer in Science


  1. Any of several instruments used to measure radiation, such as a pyrheliometer.
Show More
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.