|See also photoperiodism the period of daylight in every 24 hours, esp in relation to its effects on plants and animals|
|the offspring of a zebra and a donkey.|
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
photoperiod pho·to·pe·ri·od (fō'tō-pĭr'ē-əd)
The duration of an organism's daily exposure to light, considered especially with regard to the effect of such exposure on growth and development.
|photoperiod (fō'tō-pîr'ē-əd) Pronunciation Key
The duration of an organism's daily exposure to light, considered especially with regard to the phenomena of photoperiodism.