Literally bed-keeper or chamberlain, and not necessarily in all cases one who was mutilated, although the practice of employing such mutilated persons in Oriental courts was common (2 Kings 9:32; Esther 2:3). The law of Moses excluded them from the congregation (Deuteronomy 23:1). They were common also among the Greeks and Romans. It is said that even to-day there are some in Rome who are employed in singing soprano in the Sistine Chapel. Three classes of eunuchs are mentioned in Matthew 19:12.
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Eunuch'". "Easton's Bible Dictionary".