Monogenes (μονογενής) has two primary definitions, "pertaining to being the only one of its kind within a specific relationship" and "pertaining to being the only one of its kind or class, unique in kind".Greek-English Lexicon of the New Testament and Other Early Christian Literature (BAGD, 3rd Edition) Its Greek meaning is often applied to mean "one of a kind, one and only".LSJ Dictionary Entry Monogenēs may be used as an adjective. For example, monogenēs pais means only child, only legitimate child or special child.White, The Forgotten Trinity [Minneapolis, MN, Bethany House Publishers, 1998 Monogenēs may also be used on its own as a noun. For example, ὁ μονογενής (ho monogenēs) means "the only one", or "the only legitimate child".Richard Murphy, Background To The Bible, Servant Publications, 1978.
The word is used in Hebrews 11:17-19 (NRSVUE) to describe Isaac, son of Abraham. This is not because Isaac was the only son that Abraham had begotten, but because he was the only son of Abraham recognized by God as the legitimate son of the covenant, and so was the "only legitimate child" of Abraham according to God's promise.
The term is notable outside normal Greek usage in two special areas: in the cosmology of Parmenides and Plato and in the Gospel of John. As concerns the use by Plato there is broad academic consensus, generally following the understanding of the philosopher Proclus (412–485 AD).
Some interpretations of the word "unique" attempt to preclude birth, yet the full Greek meaning is always in the context of a child (genes). A unique child is also a born child, hence the full meaning of the word "begotten", as found in John 3:16 (NRSVUE) and other verses. Thus, we should interpret that the application of this to Jesus' begottenness refers to how Jesus is unique, perhaps in terms of the virgin birth.
Gnosticism and magic texts Platonic usage also impacted Christian usage, for example in Gnosticism. In Tertullian's Against the Valentinians, he gives the name to one of their thirty aeons as monogenes in a syzygy with makaria, Blessedness.Andrew Phillip Smith A Dictionary of Gnosticism 2009 Page 163
Friedrich Preisigke's Sammelbuch (1922) 4324,15 contains a 3rdC. AD magic invocation by an Egyptian girl called Capitolina placing a papyrus in a box to invoke various gods, pagan, Jewish and Christian, including "Iao Sabaoth Barbare..., God in Heaven, the Only-Begotten" to help her cast a love potion on a young man called Nilos: "I summon you divinities by the bitter necessities that bind you and by those carried away by the wind IO IOE PHTHOUTH EIO PHRE. The Greatest Divinity YAH SABAOTH BARBARE THIOTH LAILAMPS OSORNOPHRI EMPHERA, to God in the heavens, the only-begotten (ho Monogenes) who shakes the depths, sending out the waves and the wind. Thrust forth the spirits of these divinities wherever the box... ""285. Charm to bind Capitolina's lover Nilos to her" PGM XV1-21 Provenance unknown 3rd Century AD. Women and society in Greek and Roman Egypt: a sourcebook by Jane Rowlandson p.360"Λαιλαμψ Οσορνοφρι Βαρβαρε εν τω ουρανω θεος, ο μονογενης" F. Büchsel, Hinweis auf einen Liebeszauber ThWNT IV p746. Similar content is found in: Karl Preisendanz Greek Magical Papyri (1973) Vol.1 p124."εισακουσον μου, ο εις, μονογενης" R. Wunsch Antike Fluchtafeln (Ancient Curse Tablets, 1912) 4,36.Strecker G. Die Johannesbriefe p.233 "ορκιζωσε τον θεον... τον μονογην τον εξ αυτου αναφανεντα" The problem with magical inscriptions on papyri, walls or ostraca is firstly, dating the source, and secondly, that magical spells by nature tend to be syncretic. In the example provided above, lovestruck Capitolina summons "all the divinities" to release the spirits of "all who drowned in the Nile, the unmarried dead", et cetera to sway the heart of her young man, and, yet she may not have known enough about Judaism or Christianity, or even Gnostic Christianity, to know whether "YAHWEH SABAOTH" and "the Only-Begotten" were the same god or not.
Interpretation of New Testament usage
Some aspects of the meaning and/or the semantic range of monogenēs in the New Testament are disputed. Lexicons of the New Testament both reflect and determine debate: Bauer BDAGArndt, W., Danker, Friedrich W., & Bauer, W. (2000). A Greek-English lexicon of the New Testament and other early Christian literature (3rd ed.) (658). Chicago: University of Chicago Press: "See also Hdb. on vs. 18 where, beside the rdg. μονογενὴς θεός (considered by many the orig.) an only-begotten one, God (acc. to his real being; i.e. uniquely divine as God’s son and transcending all others alleged to be gods) or a uniquely begotten deity (for the perspective s. J 10:33–36), another rdg. ὁ μονογενὴς υἱός is found. MPol 20:2 in the doxology διὰ παιδὸς αὐτοῦ τοῦ μονογενοῦς Ἰησοῦ Χριστοῦ. Some (e.g. WBauer, Hdb.; JBulman, Calvin Theological Journal 16, ’81, 56–79; JDahms, NTS 29, ’83, 222–32) prefer to regard μ. as somewhat heightened in mng. in J and 1J to only-begotten or begotten of the Only One, in view of the emphasis on γεννᾶσθαι ἐκ θεοῦ (J 1:13 al.); in this case it would be analogous to πρωτότοκος (Ro 8:29; Col 1:15 al.)." Kittel TDNTTheological Dictionary of the New Testament edited by Gerhard Kittel, English edition (Grand Rapids: Eerdmans, 1967), pp. 737-41. Hermann Martin Friedrich Büchsel on μονογενής (and 1 of 14 footnotes) Balz EDNTBalz, Horst R., & Schneider, Gerhard. (1990-). Vol. 2: Exegetical dictionary of the New Testament (440). Grand Rapids, Mich.: Eerdmans: "Μονογενής means only in all the Lukan passages. In 7:12 (L) it is used of the son born to the widow of Nain. The Gospel writer has inserted μονογενής in 8:42 in the account of the healing of Jairus’s daughter (cf. Mark 5:23: τὸ θυγάτριόν μου) and in 9:38 in the pericope on the epileptic boy (cf. Mark 9:17: τὸν υἱόν μου). In these passages μονογενής intensifies the significance of Jesus’ miracles." Friberg ALGNTFriberg, Timothy, Friberg, Barbara, & Miller, Neva F. (2000). Vol. 4: Analytical lexicon of the Greek New Testament. Baker's Greek New Testament library (266). Grand Rapids, Mich.: Baker Books: "μονογενής, ές of what is the only one of its kind of class unique; (1) an only child born to human parents one and only (LU 7.12; 8.42); substantively only child (LU 9.38); (2) as a child born in a unique way; (a) used of God’s Son Jesus only, only begotten; substantively (JN 1.14); (b) used of Abraham’s son Isaac only; substantively ὁ μ. his only true son (HE 11.17)"
Begetting The entrance of "only begotten" into the English Bible was not directly from mono-genes, but from the Latin of the Vulgate, which reads uni-genitus (one-begotten):David Ewert A general introduction to the Bible: from ancient tablets to modern translations 1990 p230
John 3:16 sic enim dilexit Deus mundum ut Filium suum unigenitum daret ut omnis qui credit in eum non pereat sed habeat vitam aeternam. (Latin Vulgate) John 3:16 God lufede middan-eard swa þæt he sealde hys akennedan sune þæt nan ne for-wurðe þe on hine ge-lefð. Ac habbe þt eche lyf. (Hatton Gospels c.1160 AD) John 3:16 For God lovede so the world, that he yaf his oon bigetun sone, that each man that bileveth in him perishe not, but have everlastynge lijf.(Wycliffe's Bible 1395 AD)
The meaning of monogenēs was part of early Christian christological controversy regarding the Trinity. It is claimed that Arian arguments that used texts that refer to Christ as God's "only begotten Son" are based on a misunderstanding of the Greek word monogenēs,Wayne A. Grudem, Jeff Purswell Bible Doctrine: Essential Teachings of the Christian Faith 1999- Page 113 and that the Greek word does not mean "begotten" in the same sense as begetting children, but instead means "having no peer, unique".Richard Abanes Today's Mormonism: Understanding Latter-Day Saints 2007 Page 191Edward L. Dalcour A definitive look at oneness theology: defending the tri-unity of God 2005
Alternatively, in favour of the interpretation that the word monogenēs does carry some meaning related to begetting, is the etymological origin mono- (only) + -genes (born, begotten).Kenneth L. Barker, Edwin H. Palmer The NIV: the making of a contemporary translation 1986 p121
The question is whether the etymological origin was still "live" as part of the meaning when the New Testament was written, or whether semantic shift has occurred. Limiting the semantic change of monogenes is that the normal word monos is still the default word in New Testament times, and that the terms co-exist in Greek, Latin and English: Greek monos → Latin unicus → English only Greek mono-genes → Latin uni-genitus → English only-begotten
There is also the question of how separate birth and beggeting, the cited uses of monogenēs in the sense of "unique", truly are from the idea of genēs. For example, the ending -genes is arguably not redundant, even in the sense of "only", just as when Clement of Rome (96 AD), and later Origen, Cyril and others, employ monogenes to describe the rebirth of the phoenix.
At issue is whether Clement is merely stressing monos unique, or using monogenes to indicate unique in its method of rebirth, or possibly that there is only one single bird born and reborn. Likewise in Plato's Timaeus, the "only-begotten and created Heaven", is still unique in how it is begotten, in comparison to the begetting of animals and men, just as Earth and Heaven give birth to Ocean and Tethys. Of the Liddell Scott references for "unique" (monogenes being used purely as monos) that leaves only Parmenides, which (as above) is no longer considered a likely reading of the Greek text.
Additionally the New Testament frame of reference for monogenes is established by uses of the main verb "beget", and readings of complementary verses:
Heb. 1:5 (NRSVUE) "For to which of the angels did God ever say, "You are my Son; today I have begotten you"? Or again, "I will be his Father, and he will be my Son?" (citing Ps. 2:7, Acts 13:33, Heb. 5:5)
1 John 5:18 "We know that those who are born of God do not sin..."Kittel TDNT Büchsel on μονογενής Op. cit. "It is not wholly clear whether μονογενής in Jn. denotes also the birth or begetting from God; it probably does, Jn. calls Jesus ὁ γεννηθεὶς ἐκ τοῦ θεοῦ, 1 Jn. 5:18. Though many will not accept this, he here understands the concept of sonship in terms of begetting. For him to be the Son of God is not just to be the recipient of God's love. It is to be begotten of God. This is true both of believers and also of Jesus. For this reason μονογενής probably includes also begetting by God. To be sure, Jn. does not lift the veil of mystery which lies over the eternal begetting. But this does not entitle us to assume that he had no awareness of it. Johannine preaching and doctrine is designed to awaken faith, 20:30 f., not to give full and systematic knowledge. Hence it does not have to dispel all mysteries."
Uniqueness This issue overlaps with, and is interrelated with, the question of begetting above. Interpretation of the uniqueness of monogenes in New Testament usage partly depends on understanding of Hellenistic Jewish ideas about inheritance. Philo stated: On Abraham 194: "In the second place, after he [Abraham] had become the father of this [Isaac] his loved-and-only (agapetos kai monos) son, he, from the moment of his birth, cherished towards him all the genuine feelings of affection, which exceeds all modest love, and all the ties of friendship which have ever been celebrated in the world."Philo On Abraham