Dictionary entry

μεγαλαυχέω

G. Abbott-Smith's A Manual Greek Lexicon of the New Testament

μεγαλ-αυχέω, -ῶ (= μεγάλα αὐχέω),

[in LXX: Ez 16:50 (גּבהּ), al.;]

to boast great things: Ja 3:5 (Rec. for μεγάλα αὐχεῖ, WH).†