dyad

From Ancient Greek δυάς (duás), δυάδ- (duád-) from δύο (dúo, “two”), from Proto-Indo-European *duwó, *duwéh₃ (*dwóh₁).[1]

dyad (plural dyads)

1. A set of two elements treated as one; a pair.
   • 1908, W. D. Ross, Metaphysics, translation of original by Aristotle:

     ... positing a dyad and constructing the infinite out of great and small, instead of treating the infinite as one, is peculiar to him; ...

   • 2019 January 29, Tom Bissell, “An Anti-Facebook Manifesto”, in New York Times‎:

     McNamee describes their grip on the company as “the most centralized decision-making structure I have ever encountered in a large company.” Their power dyad is possible only because Facebook’s “core platform,” as McNamee puts it, is relatively simple: It “consists of a product and a monetization scheme.”

2. (music) Any set of two different pitch classes.
3. A pair of things standing in particular relation; dyadic relation.
   • "For each individual in a specific dyad (i.e., mother-offspring, offspring-father, sibling-sibling),..." Debra Lieberman, John Tooby, and Leda Cosmides - The evolution of human incest avoidance mechanisms: an evolutionary psychological approach, p. 20
4. (chemistry) An element, atom, or radical having a valence or combining power of two.
5. (biology) A secondary unit of organisation consisting of an aggregate of monads.

• dyadic

• duad
• monad
• pair
• triad
• interval
• trichord
• hexachord
• tetrachord

• Addy, D-Day, Dady, addy