heterogeneous [E17th] Heterogeneous ‘diverse’ and its opposite homogeneous [M17th] ‘alike’ make use of two useful prefixes derived from Greek—hetero- ‘other, different’ and homo- ‘same’—combined with a second half derived from Greek genos ‘kind’. Homogenized milk [E20th] has been treated so that the cream does not separate from the rest, and it is the same throughout. The two prefixes are often found, particularly in science, in contrasting pairs such as heterosexual [L19th], those who are attracted by the other sex, and homosexual [L19th], those attracted by the same sex. Hetero- also gives us heterodox [M17th] for those who hold opinions other than those which are orthodox [LME], formed from Greek combining forms ortho- ‘right’ and -dox ‘opinion’; and homo- gives us (via German, hence the different spelling) homeopathy [E19th], literally ‘like suffering’, for a system that treats symptoms with medicine which causes similar symptoms, and homogenize.