Emasculation is the removal of the genitalia of a male, both the penis and the testicles. Removal of the testicles alone is castration.
By extension, the word has also come to mean to render a male less of a man, or to make a male feel less of a man by humiliation. This metaphorical usage of the word is much more common than the application of its literal meaning. It can also mean the reduction or removal of force behind a statute or legislation: for example, "the Triennial Act was emasculated by the Cavalier Parliament".
The removal of male (pollen) parts of a plant, largely for controlled pollination and breeding purposes, is also called emasculation.
See also