'non-Alsacean' is formed in English by the negative prefix 'non-' (from Latin 'non', meaning 'not') attached to 'Alsacean', which denotes relation to 'Alsace' (the region name).

'Alsace' comes into English via French 'Alsace' (Modern French) and earlier Medieval Latin 'Elassacia'; the English adjective 'Alsacean' (or 'Alsatian') was created by adding the adjectival suffix '-ean'/'-ian' to the place name. The compound 'non-Alsacean' is a modern formation using the productive English prefix 'non-'.

Originally place names like 'Alsace' simply identified a region; over time adjectival forms ('Alsacean', 'Alsatian') and negative compounds ('non-Alsacean') have been used to indicate belonging or lack of belonging—'non-Alsacean' has retained the straightforward meaning 'not from or characteristic of Alsace'.