Lewis Short
(adjective) : bĭmātris, e, bis - mater
* Having two mothers, poet. epithet of Bacchus (v. Bacchus init.): satumque iterum solumque bimatrem,Ov. M. 4, 12; Hyg. Fab. 167; Anthol. Lat. 1, 19, 2 (where it is scanned bīmăter).
Charlton T. Lewis, Charles Short, A Latin Dictionary