photoperiod noun. ['fǝʊtǝʊpɪǝrɪǝd] E20.
[from PHOTO- + PERIOD noun.]
Biology. The period of daily illumination which an organism receives; the length of this period which is most effective in stimulating reproduction or some other function.

■ photoperi'odic adjective of, pertaining to, or influenced by photoperiods E20.

■ photoperi'odically adverb by means of or with regard to photoperiods M20.

■ photoperio'dicity noun photoperiodism M20.

■ photo'periodism noun the phenomenon whereby many plants and animals are stimulated or inhibited in reproduction and other functions by the lengths of the daily periods of light and darkness to which they are subjected E20.

[TahlilGaran] English Dictionary ▲