The meaning of Dyads and additional information.

Dyad(a.) 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.

Dyad(n.) Two units treated as one; a couple; a pair.

Dyad(n.) An element, atom, or radical having a valence or combining power of two.