Is it farther or further?
1610s (implied in castrated), back-formation from castration (q.v.), or from Latin castratus, past participle of castrare. The figurative sense is attested earlier (1550s). Related: Castrating.
castrate cas·trate (kās'trāt')v. cas·trat·ed, cas·trat·ing, cas·trates
To remove the testicles of a male; emasculate.
To remove the ovaries of a female; spay.