Bailly
v. Ἀμφικτίονες.
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LSJ
ων, οἱ, Amphictyons, deputies of states associated in an ἀμφικτυονία, e.g. at Onchestos, Str. 9.2.33; Calauria, 8.6.14; Delos, Ath. 6.234e; esp. at Delphi, D. 5.14, al., Aeschin. 2.115, etc. ; Ἀμφικτίονες IG 2.545.16, al., and this form seems to preserve the etym., v. ἀμφικτίονες ; sg. in Lib. Decl. 17.10, al.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)