English
dyad
Dyad comes from Ancient Greek δυάς ‘a group of two’, and goes back to Proto-Indo-European *duwó.
- Proto-Indo-Europeanc. 4500–2500 BCE*duwóreconstructed
- Proto-Hellenicc. 2200–1600 BCE*dúworeconstructed
- Ancient Greekc. 800–300 BCEδύοdúo‘two’
- Ancient Greek, derivedc. 800–300 BCEδυάςduás‘a group of two’
- Englishearliest quotation 1908dyad
attested reconstructed ? uncertain or disputed
Lineage
- Proto-Indo-Europeanc. 4500–2500 BCE*duwóreconstructed
- Proto-Hellenicc. 2200–1600 BCE*dúworeconstructed
- Ancient Greekc. 800–300 BCEδύοdúo‘two’
- Ancient Greek, derivedc. 800–300 BCEδυάςduás‘a group of two’
- Englishearliest quotation 1908dyad
Earliest quotation: 1908, W. D. Ross, Metaphysics Book I: “[…] positing a dyad and constructing the infinite out…”
The story
The mathematics sense was coined by American scientist Josiah Willard Gibbs in 1884 in the second half of his book Elements of Vector Analysis.
Every English word from Proto-Indo-European *duwó
Today it means
noun A set of two elements treated as one; a pair.
Language periods are conventional ranges, not dates for this word.
Etymograph / Proto-Indo-European *duwó / dyad