Emasculation is the removal of both the penis and the testicles, the external male sex organs. It differs from castration, which is the removal of the testicles only, although the terms are sometimes used interchangeably. The potential medical consequences of emasculation are more extensive than those associated with castration, as the removal of the penis gives rise to a unique series of complications. There are a range of religious, cultural, punitive, and personal reasons why someone may choose to emasculate themselves or another person. Consensual emasculation may be seen as a form of body modification that enhances a recipient's identification with their community or sense of self. By comparison, non-consensual emasculations, such as those performed punitively or accidentally, may constitute genital mutilation. The medical treatment for an emasculated person differs depending on whether the procedure was consensual.

The term emasculation may be used metaphorically to refer to the loss of a man's masculinity. A man is said to be emasculated when he loses or is deprived of a characteristic traditionally associated with being a man, such as power or independence.