1708, from bomb (n.) + shell (n.). The figurative sense of "shattering or devastating thing or event" attested from 1860. In reference to a pretty woman (especially a blonde) it is attested from 1942 ("Bombshell" as title of a movie starring blond U.S. actress Jean Harlow (1911-1937) is from 1933).[bombshell etymology, bombshell origin, 英语词源]