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photoperiod

[foh-tuh-peer-ee-uh d]
noun Biology.
  1. the interval in a 24-hour period during which a plant or animal is exposed to light.

Origin of photoperiod

First recorded in 1915–20; photo- + period
Related formspho·to·pe·ri·od·ic [foh-tuh-peer-ee-od-ik] /ˌfoʊ təˌpɪər iˈɒd ɪk/, pho·to·pe·ri·od·i·cal, adjectivepho·to·pe·ri·od·i·cal·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for photoperiod

photoperiod

noun
  1. the period of daylight in every 24 hours, esp in relation to its effects on plants and animalsSee also photoperiodism
Derived Formsphotoperiodic, adjectivephotoperiodically, adverb
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
photoperiod in Medicine

photoperiod

[fō′tō-pîr′ē-əd]
n.
  1. The duration of an organism's daily exposure to light, considered especially with regard to the effect of such exposure on growth and development.
Related formspho′to•pe′ri•od′ic (-ŏd′ĭk) null adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
photoperiod in Science

photoperiod

[fō′tō-pîr′ē-əd]
  1. The duration of an organism's daily exposure to light, considered especially with regard to the phenomena of photoperiodism.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.