castration [LME] Castration goes back, via French, to Latin castrationem from castrare ‘to castrate’, which probably goes back to a word for ‘a knife’. The Latin has a much wider range of senses than the modern English, including ‘to prune, expurgate, deprive of vigour’, and all these senses were once used in English. An old name for a beaver was castor, taken from Greek. The name seems ultimately to go back to Castor, ‘he who excels’, one of the Divine Twins of Greek mythology. But because of the similarity of the sounds, a legend grew up that the beaver got its name because it would castrate itself when hunted rather than be killed for the glands it has that were used as a healing oil and in perfumery. The modern plant-basted castor oil [M18th] may get its name from this.