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Webster 1913 Edition
Tetrad
Tet′rad
,Noun.
[L.
tetras
, -adis
, Gr. [GREEK], [GREEK]: cf. F. tétrade
.] 1.
The number four; a collection of four things; a quaternion.
2.
(Chem.)
A tetravalent or quadrivalent atom or radical;
as, carbon is a
. tetrad
Webster 1828 Edition
Tetrad
TET'RAD
,Noun.