a man who does not father children, whether castrated, born unable to, or unmarried by choice; also a title for a senior officer of a royal court
Greek used this word for a man who had been castrated. Because the royal courts of Persia, Egypt, and their neighbors staffed their treasuries and inner chambers with such men, the word slid easily into a second use: it became a way of naming a trusted senior officer, whether or not the man in question had actually been cut. That double life is why the word can sit in a verse beside a plain word for a ranking official (δυνάστης) without simply repeating it.
Jesus uses the word three times in a single sentence in Matthew 19:12, and each time it means something different: a man born unable to father children, a man castrated by other people (the matching verb there is εὐνουχίζω, "to make a eunuch of"), and a man who has set marriage aside for the sake of God's reign. The third is the surprise. It takes a word for a bodily condition, and usually a shameful one, and turns it into a description of a free choice.
Behind both uses stands a promise. Deuteronomy 23:1 shut a castrated man out of the assembly, and Isaiah 56:3-5 answers that exclusion head on, promising such men a name inside God's house better than sons and daughters. So when Luke sets an Ethiopian court official reading Isaiah on a desert road and calls him by this word five times over, the promise is the point of the scene. Hebrew tells the same story with its own word for these men (סָרִיס).
Nuances
Who the third group in Matthew 19:12 are.
- majorityA figure of speech: men who freely give up marriage and children for the sake of God's reign.; Ulrich Luz, Matthew 8-20, Hermeneia (2001); W. D. Davies and Dale C. Allison, The Gospel According to Saint Matthew, ICC, vol. 3 (1997); Josef Schneider, "εὐνοῦχος, εὐνουχίζω," in Theological Dictionary of the New Testament (TDNT) 2:765-768
- minorityA backward glance at the divorce saying just before it: men bound to stay unmarried once a marriage has broken.; Quentin Quesnell, "Made Themselves Eunuchs for the Kingdom of Heaven (Mt 19,12)," CBQ 30 (1968)
- minorityA retort: Jesus takes up a slur aimed at himself and his unmarried followers and turns it into a claim about the kingdom.; Josef Blinzler, "Εἰσὶν εὐνοῦχοι: Zur Auslegung von Mt 19,12," ZNW 48 (1957)
Whether Luke's word for the Ethiopian marks him as a physically castrated man or is simply the title of a senior court officer.
- majorityA physically castrated man. Luke already supplies a separate word for his office in the same verse, and the episode turns on Isaiah, whose promise to such men in Isaiah 56 answers their exclusion in Deuteronomy 23:1.; F. Scott Spencer, "The Ethiopian Eunuch and His Bible: A Social-Science Analysis," BTB 22 (1992); Brittany E. Wilson, "Neither Male nor Female: The Ethiopian Eunuch in Acts 8.26-40," NTS 60 (2014); Craig S. Keener, Acts: An Exegetical Commentary, vol. 2 (2013)
- minorityA title of office, so the man need not have been castrated; in Greek the word could designate a high court official on its own.; Ernst Haenchen, The Acts of the Apostles: A Commentary (1971); BDAG, s.v. εὐνοῦχος