weaken - lessen the strength of; "The fever weakened his body"

caponise, caponize - convert a cock into a capon

geld, cut - cut off the testicles (of male animals such as horses); "the vet gelded the young horse"

desex, desexualise, desexualize, sterilise, sterilize, unsex, fix - make infertile; "in some countries, people with genetically transmissible disbilites are sterilized"

unmanful, unmanlike, unmanly - not possessing qualities befitting a man