fortfort

Fort comes from Middle French fort ‘strong’, from Latin fortis ‘strong’, from Old Latin forctis, from Proto-Italic *forktis.

1. Proto-Italicc. 1500–700 BCE*forktis¹‘strong’reconstructed
2. Old Latinc. 700–75 BCEforctis¹‘strong’
3. Latinc. 75 BCE–200 CEfortis²‘strong’
4. Old Frenchc. 842–1400fort³‘strong’
5. Middle Frenchc. 1400–1600fort⁴‘strong’
6. Middle Englishc. 1150–1500fort⁴
7. Englishtodayfort⁴‘fort, stronghold’

1. ¹ Wiktionary, Latin fortis
2. ² Wiktionary, Old French fort
3. ³ Wiktionary, Middle French fort
4. ⁴ Wiktionary, English fort