Know how to use "fewer" and "less"? Find out.
1620s, from Medieval Latin heterogeneus, from Greek heterogenes, from heteros "different" (see hetero-) + genos "kind, gender, race stock" (see genus). Earlier in same sense was heterogeneal (c.1600).
heterogeneous het·er·o·ge·ne·ous (hět'ər-ə-jē'nē-əs, -jēn'yəs)adj. Composed of parts having dissimilar characteristics or properties.