ἄμ

β, π, φ, μ
ἄμ, for ἀνά, before words beginning with β, π, φ, μ, e.g. ἂμ βωμοῖσι, ἂμ μέσον, ἂμ πεδίον, ἂμ πέλαγος, ἂμ φυτά; also compds., as ἀμπαύω:—mostly Dor., as in Pi., but also in Hom., sts. in Trag.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project