[1] : The Collaborative International Dictionary of English v.0.48

dyad \dy"ad\, n. l. dyas, dyadis, the number two. gr. ?: cf. f.
   dyade. see two, and cf. duad.
   1. two units treated as one; a couple; a pair.
      1913 webster

   2. chem. an element, atom, or radical having a valence or
      combining power of two.
      1913 webster
see also:
duad 

[2] : The Collaborative International Dictionary of English v.0.48

dyad \dy"ad\, a. 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
   valence.
   1913 webster
see also:
valence 

[3] : WordNet (r) 2.0

dyad
     n : two items of the same kind syn: couple, pair, twosome,
          twain, brace, span, yoke, couplet, distich,
         duo, duet, duad
see also:
couple pair twosome twain brace span 
yoke couplet distich duo duet 
duad 

[4] : Moby Thesaurus II by Grady Ward, 1.0

21 moby thesaurus words for "dyad":
   both, brace, couple, couplet, distich, double harness, doublet,
   duad, duet, duo, match, mates, pair, set of two, span, team,
   the two, twain, two, twosome, yoke

Dyad >> D Words
Dyad, definition of term: Dyad
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