The headword, an old epic epithet of children with diverse connotations and of uncertain origin (Chantraine s.v. thlu/getos), is an adjective in the feminine genitive singular; see generally LSJ s.v. thlu/getos, -h, -on (darling, only (child), last born, estranged). Evidently extracted from somewhere, the headword form occurs only once outside lexicography: Nonnus, Dionysiaca 6.106 (web address 1). There Demeter (delta 483 and OCD(4) s.v.), in a context that supports most if not all of the above senses of the headword, receives prophesy of the ravishing of her cherished daughter, Persephone (kappa 2077 gloss and OCD(4) s.v. Persephone/Kore). Adler also cites Lexicon Ambrosianum 305 and Boysen's Lexicon Seguerianum. [In her critical apparatus she reports that the lemma reads *thlu/getos in ms G.]
[1] The gloss is a two-ending adjective in the masculine and feminine nominative singular; cf. mu 1224, alpha 154 (gloss), and see generally LSJ s.v. monogenh/s, -e/s. The headword is identically glossed in the Synagoge, Lexica Segueriana 386.29, and Photius' Lexicon. Similar entries are found in Hesychius; ps.-Herodian, Partitiones 133.3; and Apion, Fragmenta de glossis Homericis (Ludwich) 75.101.15.
[2] The secondary lemma is the masculine accusative singular form of the headword adjective, apparently quoted from Homer, Iliad 13.470; cf. the scholia there. Its gloss is the masculine/feminine accusative singular of the headword gloss; cf. Hesychius s.v. thluge/thn (feminine accusative singular), with this same gloss. The secondary lemma and gloss are identical in the glossing lexica of n.1, except that Lexica Segueriana loc. cit. omits the secondary gloss.
[3] Homer, Iliad 9.143 (web address 2). Before Nestor and the assembled Greeks Agamemnon proffers what he intends to be an enticement to Achilles: the sulking warrior might be brought up like a son, indeed as cherished as Orestes (OCD(4) s.v. and Hainsworth, p. 76). The fact is that this is an unwitting insult.
[4] Elucidating yet another sense of the headword, not only cherished in particular and not an only child, but the last child among the offspring. [Adler reports that mss GV transmit genh/setai: after whom no other will come into being; also that e(/teros (after whom no other) was added in the Suda's editio princeps.]
[5] From a scholion (= D scholia) to Homer, Iliad 3.175 (web address 3); cf. Etymologicum Magnum 757.18 (Kallierges), for which Adler also cites Etymologicum Genuinum as identical. [Adler reports that ms V reads o)yi/mws, lately.]
[6] Reading gs for goni/as in the text (which appears to be an error), this note follows a scholion (= D scholia) to Homer, Iliad 3.175 (web address 3). [Adler reports that this addendum appears in the margin of ms M and is omitted by other mss.]