unionunion

Union comes from Middle English unyoun, from Old French union, from Late Latin ūniō ‘oneness’, from Latin ūnus ‘one’, ultimately from PIE *h₁óynos ‘one’.

1. Proto-Indo-Europeanc. 4500–2500 BCE*h₁óynos¹‘one’reconstructed
2. Proto-Italicc. 1500–700 BCE*oinos¹‘one’reconstructed
3. Old Latinc. 700–75 BCEoinos¹
4. Latinc. 75 BCE–200 CEūnus²‘one’
5. Late Latinc. 200–600 CEūniō²‘oneness’
6. Old Frenchc. 842–1400union²
7. Middle Englishc. 1150–1500unyoun²
8. Englishearliest quotation c. 1599–1602union²

1. ¹ Wiktionary, Latin unus
2. ² Wiktionary, English union
3. Earliest quotation in Wiktionary’s entry: c. 1599–1602, William Shakespeare, The Tragedie of Hamlet, Prince of Denmarke: “And in the cup an union shall he throw,…”.