Emasculation is the removal of the genitalia (castration) of a male, notably the penis and/or the testicles.
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, e.g. "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.