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Dictionary of Medieval Names
from European Sources

Agena f. Old French agin lengthened from Proto-Germanic *agio 'blade', or a pet form of any of various names with this prototheme.

France
Latin
c823 Agena (nom) irminon-vol2 51
Cite as: S.L. Uckelman. "Agena". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2015, no. 3. http://dmnes.org/2015/3/name/Agena.