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infradian Syllabification: in·fra·di·an
Pronunciation: /inˈfrādēən/

Definition of infradian in English:


(Of a rhythm or cycle) having a period of recurrence longer than a day; occurring less than once a day. Compare with ultradian.
Example sentences
  • The crayfish Procambarus clarkii is a nocturnal organism that displays a span of overt circadian and infradian rhythms to adapt to daily and seasonal environmental lighting changes.
  • The circadian rhythm resides with an infradian rhythm of lunar 28-day cycles, seasonal cycles of cold and hot as well as shifting light and dark.
  • In this paper, a presumptive role for infradian hormonal rhythms is considered.


Mid 20th century: from infra- 'below' (i.e., expressing a lower frequency), on the pattern of circadian.

Definition of infradian in:
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