ἀδελφός

• ἀδελφεός (adelpheós), ἀδελφειός (adelpheiós) – Epic, Ionic, Lyric
• ἀδελφιός (adelphiós) – Boeotian
• ἀδελφιός (adelphiós), ἀδευφιός (adeuphiós) – Cretan

From Proto-Indo-European *sm̥-gʷelbʰ- (“one/same womb”), from *gʷelbʰ- (“womb”), equivalent to ἁ- (ha-, copulative prefix) +‎ δελφύς (delphús, “womb”). The initial /h/ is lost due to Grassmann's Law. Cognate to Sanskrit सगर्भ्य (ságarbhya, “brother”).

ᾰ̓δελφός • (adelphós) m (feminine ᾰ̓δελφή, neuter ᾰ̓δελφόν); first/second declension

(Attic)

1. brotherly or sisterly
   • 467 BCE, Aeschylus, Seven Against Thebes 811:

     οὕτως ἀδελφαῖς χερσὶν ἠναίρονθ’ ἅμα;

     hoútōs adelphaîs khersìn ēnaíronth’ háma?

     • 1926 translation by Herbert Weir Smyth

       Then with hands so fraternal did they each kill the other together?

2. double
3. closely related, akin

ἀδελφός • (adelphós) m (genitive ἀδελφοῦ); second declension

1. brother

• Greek: αδελφός (adelfós), αδερφός (aderfós)

• ἀδελφός in Liddell & Scott (1940) A Greek–English Lexicon, Oxford: Clarendon Press
• ἀδελφός in Liddell & Scott (1889) An Intermediate Greek–English Lexicon, New York: Harper & Brothers
• ἀδελφός in the Diccionario Griego–Español en línea (2006–2019)
• G80 in Strong’s Exhaustive Concordance to the Bible, 1979
• Woodhouse, S. C. (1910) English–Greek Dictionary: A Vocabulary of the Attic Language‎, London: Routledge & Kegan Paul Limited.
  • akin idem, page 21.
  • brother idem, page 101.
  • brotherly idem, page 101.
  • cognate idem, page 142.
  • fraternal idem, page 343.
  • german, germane idem, page 357.
  • kindred idem, page 469.
  • like idem, page 491.
  • sister idem, page 779.
• Bauer, Walter et al. (2001) A Greek–English Lexicon of the New Testament and Other Early Christian Literature, Third edition, Chicago: University of Chicago Press
• Etymologicum Magnum (ΜΕΓΑ ΕΤΥΜΟΛΟΓΙΚΟΝ online)