1. An individual who has been deprived of testes; such as, a eunuch (human being), or an ox or gelding (farm animals).
2. Referred to as gelding, neutering, orchiectomy, and orchidectomy; this practice refers to any action, surgical, chemical, or otherwise, by which a biological male loses use of the testes.

In Europe, when females were not permitted to sing in church or cathedral choirs in the Roman Catholic Church, boys were sometimes castrated to prevent their voices breaking at puberty and to develop a special high voice.

These men, known as castrati, were very popular in the 18th century. The practice of employing castrati lasted longest in Italian churches, most notably in the Sistine Chapel Choir.