Word Study On φιλόστοργος

φιλόστοργος appears once in the GNT (Romans 12:10) and occurs at 4 Maccabees 15:13 (LXX). William Mounce provides the definition, "tenderly affectionate." In the Testament of Abraham, Jehovah describes his patriarchal "friend" this way: φιλόξενος καὶ φιλόστοργος ἕως τέλους τῆς ζωῆς αὐτοῦ·

See https://pseudepigrapha.org/docs/text/TAbr

Xenophon, Cyropedia 1.3.2: Ὡς δὲ ἀφίκετο τάχιστα καὶ ἔγνω ὁ Κῦρος τὸν Ἀστυάγην τῆς μητρὸς πατέρα ὄντα, εὐθὺς οἷα δὴ παῖς φύσει φιλόστοργος ὢν ἠσπάζετό τε αὐτὸν ὥσπερ ἂν εἴ τις πάλαι συντεθραμμένος καὶ πάλαι φιλῶν ἀσπάζοιτο, καὶ ὁρῶν δὴ αὐτὸν κεκοσμημένον καὶ ὀφθαλμῶν ὑπογραφῇ καὶ χρώματος ἐντρίψει καὶ κόμαις προσθέτοις, ἃ δὴ νόμιμα ἦν ἐν Μήδοις

4 Maccabees 15:13: ὦ φύσις ἱερὰ καὶ φίλτρα γονέων καὶ γένεσι φιλόστοργε καὶ τροφεία καὶ μητέρων ἀδάμαστα πάθη

Josephus, AJ 7.250-252: φύσει γὰρ ὢν φιλόστοργος πρὸς ἐκεῖνον μᾶλλον συμπαθῶς εἶχεν.

BDAG: φιλόστοργος, ον (X.+; inscr.; PMich. 148 II, 9 [I AD]; 4 Macc 15:13; Philo; Jos., Ant. 7, 252al.) loving dearly τῇ φιλαδελφίᾳ εἰς ἀλλήλους φιλόστοργοι devoted to one another in brotherly love Ro 12:10.—CSpicq, Φιλόστοργος: RB 62, ’55, 497-510. M-M.*

Greek-English Lexicon of the Septuagint, page 1246: φιλόστοργος,-ος,-ον+ A 0-0-0-0-1=1
4 Mc 15,13 loving dearly, yearning
Cf. SPICQ 1978a, 944-948; →NIDNTT

Ernst Kasemann, Commentary on Romans, page 345: The adjective φιλόστοργος, which is used only here in the NT, means first tenderness toward family and friends (Sanday and Headlam; H. W. Schmidt). Extended in the koine to the political and religious sphere, it then denotes respectful and sacrificial conduct (Spicq, "Φιλόστοργος," 507ff.).

See LSJ: https://lsj.gr/wiki/%CF%86%CE%B9%CE%BB%CF%8C%CF%83%CF%84%CE%BF%CF%81%CE%B3%CE%BF%CF%82