erogenous (adj.) Look up erogenous at Dictionary.com
formed 1889 from Greek eros "sexual love" (see Eros) + -genous "producing." A slightly earlier variant was erogenic (1887), from French érogénique. Both, as OED laments, are improperly formed. Erogenous zone attested by 1905.
In this connection reference may be made to the well-known fact that in some hysterical subjects there are so-called "erogenous zones" simple pressure on which suffices to evoke the complete orgasm. There is, perhaps, some significance, from our present point of view, in the fact that, as emphasized by Savill ("Hysterical Skin Symptoms," Lancet, January 30 1904) the skin is one of the very best places to study hysteria. [Havelock Ellis, "Studies in the Psychology of Sex," 1914]