The city is served by a transit network, which includes four international airports, nine railway terminals, numerous trams, a monorail system and one of the deepest underground rapid transit systems in the world, the Moscow Metro, the fourth-largest in the world and largest outside Asia in terms of passenger numbers, and the busiest in Europe. It is recognized as one of the city's landmarks due to the rich architecture of its 200 stations.
Moscow has acquired a number of epithets, most referring to its size and preeminent status within the nation: The Third Rome (Третий Рим), the Whitestone One (Белокаменная), the First Throne (Первопрестольная), the Forty Soroks (Сорок Сороков) ("sorok" meaning both "forty, a great many" and "a district or parish" in Old Russian).
Moscow is also one of the twelve Hero Cities. The demonym for a Moscow resident is "москвич" (moskvich) for male or "москвичка" (moskvichka) for female, rendered in English as Muscovite.
The name "Moscow" is abbreviated "MSK" (МСК in Russian).
The name of the city is thought to be derived from the name of the Moskva River. There have been proposed several theories of the origin of the name of the river. Finno-UgricMerya and Muroma people, who were among the several Early Eastern Slavic tribes which originally inhabited the area, called the river supposedly Mustajoki. It has been suggested that the name of the city derives from this term.
The original Old Russian form of the name is reconstructed as *Москы, *Mosky, hence it was one of a few Slavic ū-stem nouns. As with other nouns of that declension, it had been undergoing a morphological transformation at the early stage of the development of the language, as a result the first written mentions in the 12th century were Московь, Moskovĭ (accusative case), Москви, Moskvi (locative case), Москвe/Москвѣ, Moskve/Moskvě (genitive case). From the latter forms came the modern Russian name Москва, Moskva, which is a result of morphological generalisation with the numerous Slavic ā-stem nouns.
However, the form Moskovĭ has left some traces in many other languages, such as English: Moscow, German: Moskau, French: Moscou, Georgian: მოსკოვი, Latvian: Maskava, Ottoman Turkish: Moskov, Tatar: Мәскәү, Mäskäw, Kazakh: Мәскеу, Mäskew, Chuvash: Мускав, Muskav, etc. In a similar manner the Latin name Moscovia has been formed, later it became a colloquial name for Russia used in Western Europe in the 16th–17th centuries. From it as well came English Muscovy and muscovite.
Various other theories (of Celtic, Iranian, Caucasic origins), having little or no scientific ground, are now largely rejected by contemporary linguists.