Definify.com
Webster 1913 Edition
Pleonaste
Ple′o-naste
,Noun.
[Gr.[GREEK] abundant, rich; cf. F.
pl
éonaste
.] (Min.)
A black variety of spinel.
Webster 1828 Edition
Pleonaste
PLE'ONASTE
,Noun.
A mineral, commonly considered as a variety of the spinelle ruby. [See Ceylonite.]