biorhythmics

Etymology tree
Proto-Indo-European *gʷeyh₃-der.
Ancient Greek βῐ́ος (bĭ́os)
Ancient Greek βῐο- (bĭo-)der.
English bio-
Proto-Indo-European *ser-?
Proto-Indo-European *srew-
Proto-Indo-European *sru-dʰ-mo-s
Proto-Hellenic *hrutʰmós
Ancient Greek ῥῠθμός (rhŭthmós)bor.
Latin rhythmusder.
English rhythm
English biorhythm
Proto-Indo-European *-ikos
Proto-Italic *-ikos
Latin -icuslbor.
Old French -iquebor.
Middle English -ik
English -ic
Old English -as
Middle English -es
English -s
English -ics
English biorhythmics
From biorhythm + -ics.