photoperiod

noun

pho·​to·​pe·​ri·​od ˌfō-tō-ˈpir-ē-əd How to pronounce photoperiod (audio)
: a recurring cycle of light and dark periods of constant length
photoperiodic adjective
photoperiodically adverb

Examples of photoperiod in a Sentence

Recent Examples on the Web On the other hand, there's the findings of sleep psychiatrist Thomas Wehr, in particular his classic 1992 study called In short photoperiods, human sleep is biphasic. Neuroskeptic, Discover Magazine, 29 Apr. 2010 To time this arrival for the highest likelihood of conditions favorable to reproducing, a migratory bird tracks each day’s light length, or photoperiod, says Marilyn Ramenofsky, a behavioral endocrinologist at the University of California, Davis, who specializes in birds. Meghan Bartels, Scientific American, 20 Apr. 2023 As mentioned earlier, brood fish are housed in the same indoor tanks where scientists fool them into spawning by playing around with photoperiods and water temperature. Matt Williams, Dallas News, 9 May 2020 The prompt to begin growing a fresh set of antlers is regulated by a rise in testosterone, which is triggered by photoperiod. Andrew McKean, Outdoor Life, 26 Mar. 2020 About 10 varieties are being grown using photoperiod manipulation, which will be featured on the tours. Lauren Delgado, OrlandoSentinel.com, 9 July 2018

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

Word History

First Known Use

1920, in the meaning defined above

Time Traveler
The first known use of photoperiod was in 1920

Dictionary Entries Near photoperiod

Cite this Entry

“Photoperiod.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/photoperiod. Accessed 19 Mar. 2024.

Kids Definition

photoperiod

noun
pho·​to·​pe·​ri·​od ˌfōt-ō-ˈpir-ē-əd How to pronounce photoperiod (audio)
: a recurring cycle of light and dark periods as it affects the growth and functioning of a plant or animal

Medical Definition

photoperiod

noun
pho·​to·​pe·​ri·​od ˌfōt-ō-ˈpir-ē-əd How to pronounce photoperiod (audio)
: a recurring cycle of light and dark periods of constant length
photoperiodic adjective
photoperiodically adverb
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!