English

Adjective

circannual ‎(not comparable)

1. (biology) Occurring or having cycles of approximately annual periodicity
   • 1956, USAF School of Aerospace Medicine, Report [80-114], [1956], page 11

     […] because morbidity and mortality from cardiovascular disease also reveal statistically significant circadian and circannual rhythms.

   • 2000, Martin Hume Johnson, Barry J. Everitt, Essential Reproduction, page 110

     Circannual rhythms control reproductive function in seasonal breeders.

   • 2001, Joseph S. Takahashi, Fred W. Turek, Robert Y. Moore, Handbook of Behavioral Neurobiology, page 523

     Seasonal variations in locomotor activity are generated by a circannual clock […].

Usage notes

In practice circannual is not used comparatively. In principle, one biorhythm could be "more circannual" than another if its period were closer to a year than the other's.