early 15c., castracioun, from Latin castrationem (nominative castratio), noun of action from past participle stem of castrare "to castrate, emasculate," supposedly from a noun *castrum "knife, instrument that cuts," from PIE root *kes- "to cut" (see caste). Freud's castration complex is attested from 1914 in English (translating German Kastrationsangst).