The Collaborative International Dictionary of English v.0.48:

Monodelphia \Mon`o*del"phi*a\, n. pl. [NL., fr. Gr. mo`nos
   single + delfy`s the womb.] (Zool.)
   The group that includes all ordinary or placental mammals;
   the Placentalia. See Mammalia.
   [1913 Webster] Monodelphic