One of the more curious legacies of Coptic is a set of words in European languages that carry a fossilised Egyptian definite article. The mechanism is simple. Late Egyptian and Coptic mark a definite noun with a short prefixed element, and in many words that element stopped being felt as separable and became part of the noun itself.
When Greek speakers in Egypt took such a word over, they took the fused form, and Greek passed it on. Place names are the largest group, since a Greek administration in Egypt had constant occasion to write them down, and the same happened with the names of individuals and of institutions. The process is a reminder that Coptic was not a sealed liturgical language. For several centuries it was the ordinary spoken language of most of Egypt, in daily administrative and commercial use alongside Greek, and the enormous body of Coptic documentary material from monastic settlements, ostraca, letters, contracts, accounts and receipts, shows the language doing ordinary work rather than only carrying scripture. Arabic gradually displaced it after the seventh century, over a long period rather than at a stroke, and by the later medieval centuries it had ceased to be spoken generally. It never ceased to be read. The Coptic Orthodox Church has used it in worship continuously, and the letters have therefore been in unbroken use for something close to two thousand years.