LSJ
αἱ, (< δρῦς) Nymphs whose life depended on that of trees to which they were attached, Pl. Epigr. 14, Pherenicus ap. Ath. 3.78b; sg., Ἁμαδρυάς A.R. 2.477, Ant.Lib. 30.4.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)
Pape
αἱ, Baumnymphen, Nonn. D. 15.415 ; vgl. Ath. III.78b.
Pape, Griechisch-deutsches Handwörterbuch (3. Aufl., 1914)