Lexical Definition

‎φιλαδελφία‎ philadelphía (fil-ad-el-fee'-ah) brotherly love ^G:N-F
from ‎φιλάδελφος‎

brotherly love (kindness), love of the brethren.

• fraternal affection

Abbott-Smith

φιλαδελφία, -ας, ἡ (< φιλάδελφος), [in LXX: IV Mac 13:23, 26 14:1 * ;]
the love of brothers, brotherly love: of Christians' mutual love as brethren (v.s. ἀδελφός), Ro 12:10, I Th 4:9, He 13:1, I Pe 1:22, II Pe 1:7.†

Abbott-Smith References

Liddell-Scott-Jones

φιλαδελφία-ία, ἡ,

brotherly love, [Refs 1st c.AD+]; in NT, love of the brethren, [NT]

_{LSJ Scripture Refs: Rom.12.10}