To render incapable of reproducing sexually
He found it both amusing and a bit disconcerting that both Sidwell women's initial reaction was to castrate him.
These organisms live in cockles, oysters and other lamellibranchs and they so affect the gonads of these molluscs as to castrate and sterilize their host.
Gaia convinced Cronus to castrate Uranus.
For his terrible deeds, Gaia asked her son Cronus to castrate Uranus.