Photoperiod

[foh-tuh-peer-ee-uh d] /ˌfoʊ təˈpɪər i əd/

noun, Biology.
1.
the interval in a 24-hour during which a plant or animal is exposed to light.
/ˌfəʊtəʊˈpɪərɪəd/
noun
1.
the period of daylight in every 24 hours, esp in relation to its effects on plants and animals See also photoperiodism

photoperiod pho·to·pe·ri·od (fō’tō-pĭr’ē-əd)
n.
The duration of an organism’s daily exposure to light, considered especially with regard to the effect of such exposure on growth and development.
pho’to·pe’ri·od’ic (-ŏd’ĭk) or pho’to·pe’ri·od’i·cal (-ĭ-kəl) adj.
photoperiod
(fō’tō-pîr’ē-əd)
The duration of an organism’s daily exposure to light, considered especially with regard to the phenomena of photoperiodism.

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Photoperiodicity
[foh-tuh-peer-ee-uh-diz-uh m] /ˌfoʊ təˈpɪər i əˌdɪz əm/ noun, Biology. 1. the response, as affecting growth or reproduction, of an organism to the length of exposure to light in a 24-hour period. /ˌfəʊtəʊˈpɪərɪəˌdɪzəm/ noun 1. the response of plants and animals by behaviour, growth, etc, to photoperiods n. 1920, from photoperiod (1920, from photo- + period) […]
Photoperiodism
[foh-tuh-peer-ee-uh-diz-uh m] /ˌfoʊ təˈpɪər i əˌdɪz əm/ noun, Biology. 1. the response, as affecting growth or reproduction, of an organism to the length of exposure to light in a 24-hour period. /ˌfəʊtəʊˈpɪərɪəˌdɪzəm/ noun 1. the response of plants and animals by behaviour, growth, etc, to photoperiods n. 1920, from photoperiod (1920, from photo- + period) […]
Photophilic
[foh-tuh-fil-ik] /ˌfoʊ təˈfɪl ɪk/ adjective 1. of or relating to an organism, as a plant, that is receptive to, seeks, or thrives in light.

Photophilous
[foh-tuh-fil-ik] /ˌfoʊ təˈfɪl ɪk/ adjective 1. of or relating to an organism, as a plant, that is receptive to, seeks, or thrives in light. /fəʊˈtɒfələs/ adjective 1. (esp of plants) growing best in strong light
Photophobia
[foh-tuh-foh-bee-uh] /ˌfoʊ təˈfoʊ bi ə/ noun, Pathology. 1. an abnormal sensitivity to or intolerance of light, as in iritis. 2. an abnormal fear of light. /ˌfəʊtəʊˈfəʊbɪə/ noun 1. (pathol) abnormal sensitivity of the eyes to light, esp as the result of inflammation 2. (psychiatry) abnormal fear of or aversion to sunlight or well-lit places n. […]