Noun
(biology) Any cyclic biological or physiological pattern or activity.
(pseudoscience) Any of three sinusoidal graphs, normally plotted by computer, having a person's birthdate as origin, that are claimed to give meaningful information about emotional levels, physical energy levels, and mental/psychic sensitivity.
Source: en.wiktionary.orgTelevision has a different biorhythm than movies. I love the biorhythm of TV. Steven Spielberg
Sunday, 25 August 2002 *"Biorhythm experiment management plan", NASA, Ames Research Center. Source: Internet