# dyad

> English word · Noun · IPA /ˈdaɪ.æd/ · frequency rank #66,629

## Definitions
1. A set of two elements treated as one; a pair.
2. Two persons in an ongoing relationship; a dyadic relationship.
3. The relationship or interaction itself in reference to a couple.
4. Any set of two different pitch classes.
5. An element, atom, or radical having a valence of or combining power of two.
6. A chromosome structure, usually X- or V-shaped, consisting of two condensed sister chromatids joined by a centromere.
7. A secondary unit of organisation consisting of an aggregate of monads.
8. A tensor of order two and rank one.

## Etymology
From Ancient Greek δυάς (duás), δυάδ- (duád-) from δύο (dúo, “two”), from Proto-Indo-European *duwó, *duwéh₃ (*dwóh₁). The mathematics sense was coined by American scientist Josiah Willard Gibbs in 1884 in the second half of his book Elements of Vector Analysis.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/dyad