We examine a case of base variation related to property nouns formation: namely, -ité suffixed French nouns expressing the character proper both to those who belong/are related to a place (town, country...) and/or to the place itself (henceforth Ethnic Property Nouns: EPNs). The study is based upon an important web-extracted corpus and shows that, at large scale, speakers coin EPNs either from toponyms (PORTUGAL > PORTUGALITÉ ‘portugal-ness’ = ‘portugueseness’), from related ethnic adjectives (AFRIQUE ‘Africa’ > AFRICAIN ‘African’ > AFRICANITÉ ‘africanness’) or from both (BELGIQUE ‘Belgium’ > BELGICITÉ ‘Belgium-ness’; BELGE ‘Belgian’ > BELGITÉEPN ‘Belgianness’). Several examples testify that these base variations are unrelated to meaning but rather correlated with four formal competing constraints: among them, what we call ‘lexical pressure’ can explain the form of the output. A survey experiment is then described, which corroborates our analysis. Finally, the scope of our conclusions goes beyond French EPNs, as they apply to other word formation rules, in many languages.