BIORHYTHMS is validvalid

BIORHYTHM, a cyclic variation in an organism [n]

122,246 of 196,601 in NWL2023·also valid in CSW24

BIORHYTHM, a periodic change in the behaviour or physiology of many animals and plants (e.g. hibernation and migration) mediated by hormones which are in turn influenced by changes in day-length [n]