An officer in the court or household of a ruler, often assigned to the women’s quarters. Many of these men were castrated (having their male genitalia removed), though not always (compare Genesis 39:1). Eunuchs were public officials in:
Israel (1 Samuel 8:15; 1 Chronicles 28:1)
Persia (Esther 2:3)
Babylon (Daniel 1:3)
Eunuchs were not part of public worship in Israel (Deuteronomy 23:1), but the prophet Isaiah referred to them in the restored messianic kingdom (Isaiah 56:3–5; see Acts 8).
The Ethiopian eunuch in Acts 8:27–39 was probably in charge of the treasury. They have been credited with spreading Christianity to Ethiopia.
Jesus mentioned three kinds of eunuchs (Matthew 19:12), including those who made themselves eunuchs for the sake of the kingdom. This probably refers to those who decide never to get married to serve the kingdom (for example, John the Baptist, Jesus, and the apostle Paul).