The Collaborative International Dictionary of English v.0.48:

Amoebaeum \Am`[oe]*b[ae]"um\, n. [L. am[oe]baeus, Gr. ?,
   alternate; L. amoebaeum carmen, Gr. ? ?, a responsive song,
   fr. ? change.]
   A poem in which persons are represented at speaking
   alternately; as the third and seventh eclogues of Virgil.
   [1913 Webster]