Definition of "photoperiod" []

• The duration of an organism's daily exposure to light, considered especially with regard to the effect of the exposure on growth and development. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Taken together, our findings suggest that optimization of experimental conditions such as photoperiod may be necessary to visualize FAA in genetically modified mice."
• "The changing of day length in spring and fall triggers bird migration because "photoperiod" is the only absolutely reliable environmental cue that signals birds that it's"
• "I know rut is driving by photoperiod, but what about the effect of a really warm snap?"