dusk: [OE] In Anglo-Saxon times, dusk was an adjective meaning ‘dark in colour’ (a sense preserved today in the derived adjective dusky [16]). Its modern noun use ‘twilight’ is not recorded until as recently as the early 17th century. The Old English form of the word was dox, which was descended from the same ultimate Indo-European ancestor as Latin fuscus ‘dark’ (source of English obfuscate [16]). => dun, obfuscale
