dawn: [15] Dawn was originally formed from day. The Old English word dæg ‘day’ formed the basis of dagung, literally ‘daying’, a word coined to designate the emergence of day from night. In Middle English this became daiing or dawyng, which in the 13th to 14th centuries evolved to dai(e)ning or dawenyng, on the model of some such Scandinavian form as Old Swedish daghning. Then in the 15th century the -ing ending was dropped to produce dawn. => day
