The name civitas was applied by the Romans to each of the independent states or tribes of Gaul; in later times it adhered to the chief town of each of these states, which usually became afterwards the seat of civil government and of episcopal authority. Though there were civitates in Britain also in Roman times, the word was not adopted by the Angles and Saxons, who applied the name burh to all towns alike. In later times civitas may be found as a Latin equivalent of burh, and, in Domesday, it is frequently applied to the larger and more important byri3, bur3es, or boroughs, which were the centres of districts, and had in some cases municipal autonomy, and thus corresponded in character to the cités of France. As an English word, cité is found early in the 13th c., applied, both to foreign, and particularly ancient cities, where it is probably due to translation from Latin or French, and also to important English boroughs, such as London and Lincoln. Under the Norman kings, the episcopal sees, which were formerly often established in villages, began to be removed to the chief borough or 'city' of the diocese, as in France; and as the bishops thus went to the cities, there grew up a notion of identification between 'city' and 'cathedral town'; which was confirmed and legally countenanced when, on the establishment of the new bishoprics by Henry VIII, the boroughs in which they were set up were created 'cities'. The same title has been conferred on all (or nearly all) the places to which new bishoprics have been assigned in the 19th c. Historians and legal antiquaries have, however, always pointed out that there is no necessary connexion of 'city' with 'cathedral town', and in recent times the style and rank of 'city' have begun to be conferred by royal authority on large and important boroughs which are not episcopal seats, Birmingham being the first so distinguished in England. (See Freeman in Macmillan's Mag., May 1889.)   

     In Scotland, the style of civitas appears to have been introduced from England, after the association of the word with the episcopal seats. Here, it appears to have had no relation to the size, civil importance, or municipal standing of the place, but was freely applied in charters from the time of David I (12th c.) to every bishop's seat, even when a mere hamlet; it was only at much later dates that some of these civitates attained sufficient importance to be raised to the rank of burghs, while others remained villages. In later times, perh. not before the Reformation, civitas is found applied to Perth and Edinburgh, which were not episcopal seats, but ancient royal burghs, and seats of royalty. The vernacular form 'city' is found in the 15th c. applied to some of the burghs which were civitates, and it gradually came to be commonly used of certain of the larger of these, notably Edinburgh, Glasgow, Perth, and Aberdeen. In this sense, the royal burgh of Dundee was also created a 'city' by Royal Charter in 1889. Some of the other burghs which were formerly bishop's seats, or can show civitas in their early charters, have in recent times claimed or assumed the style of 'city', though not generally so regarded.  

I hope you didn't read the whole of that definition . . . 
Let's see what the city has become: