"treatment of diseases by chemical substances," 1906, from German Chemotherapie, coined by German biochemist Paul Ehrlich (1854-1915), from chemo- + therapie (see therapy). Especially of cancer from 1950s; short form chemo attested by 1977.
chemist
chemistry
chemo-
chemosynthesis
chemotaxis
chemotherapy
chenille
cheque
chequer
Cher
cherchez la femme