homeo- Also homoio- and homoeo-.
[Greek homoios, like or similar.]
In homeopathy (Greek patheia, suffering or feeling) disease is treated by minute doses of substances that in a healthy person would produce symptoms of the disease, so treating like with like. Homeostasis is the tendency for plant and animal populations to remain in stable equilibrium; two geometrical figures are homeomorphic if they are topologically equivalent, as a circle can be converted to a square.
Most words once written using homoeo- (homoeopath, homoeobox) or homoio- (homoiothermic) are now usually spelled with homeo- instead. Exceptions are those that are mainly historical in application, such as homoiousian, a person who held that God the Father and God the Son are of like but not identical substance.