'Moscovian' originates from English, specifically formed from the place name 'Moscow' plus the adjectival suffix '-ian' (from Latin '-ianus'), where 'Moscow' ultimately comes from Russian 'Moskva' (Москва).

'Moscovian' developed from the English place name 'Moscow', which entered English from forms like Middle English 'Moskow' and earlier from Old East Slavic 'Moskva' (the native name of the city); the suffix '-ian' was added in English to form an adjective or noun meaning 'of or from Moscow'.

Initially it simply denoted origin or relation to the city 'Moscow'; over time the word has retained that basic sense and is used both for people (n.) and for things related to the city (adj.).