Definify.com

Webster 1913 Edition

Noun.

[L.

dyas

dyadis

, the number two. Gr. [GREEK]: cf. F.

dyade

. See two, and cf.

Two units treated as one; a couple; a pair.

(Chem.)

An element, atom, or radical having a valence or combining power of two.

Adj.

(Chem.)

Having a valence or combining power of two; capable of being substituted for, combined with, or replaced by, two atoms of hydrogen;

as, oxygen and calcium are

dyad

elements

. See