WordWeight : Weighing the Words

Pronunciation : Dy"ad
Part of Speech : n.
Etymology : [L. dyas, dyadis, the number two. Gr. dyade. See two, and cf. Duad.]
Definition : 1. Two units treated as one; a couple; a pair.

2. (Chem.)

Defn: An element, atom, or radical having a valence or combining power of two.
Source : Webster's Unabridged Dictionary, 1913

Pronunciation : Dy"ad
Part of Speech : a.
Definition : Defn: 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 Valence.

(Chem.)
Source : Webster's Unabridged Dictionary, 1913