acidacid

Acid comes from French acide, from Latin acidus ‘sour’, from aceō ‘to be sour’, ultimately from PIE *h₂eḱ-.

1. Proto-Indo-Europeanc. 4500–2500 BCE*h₂eḱ-¹‘sharp’reconstructed
2. Proto-Indo-Europeanc. 4500–2500 BCE*h₂eḱéh₁yeti¹reconstructed
3. Proto-Italicc. 1500–700 BCE*akēō¹reconstructed
4. Latinc. 75 BCE–200 CEaceō¹‘to be sour’
5. Latinc. 75 BCE–200 CEacidus¹‘sour’
6. Frenchc. 1600–presentacide¹‘acid’
7. Englishearliest quotation 1864acid¹

1. ¹ Wiktionary, English acid
2. Earliest quotation in Wiktionary’s entry: 1864, Anthony Trollope, The Small House at Allington: “His voice was as stern and his face as…”.