- (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 that are supposed to give meaningful information about emotional levels, physical energy levels, and mental/psychic sensitivity.
First coined 1960, from bio- + rhythm
biorhythm - Medical Definition
- bi′o·rhyth′mic (-rĭth′mĭk)