inappropriacy
noun [ U ] language specialized uk/ˌɪn.əˈprəʊ.pri.ə.si/ us/ˌɪn.əˈproʊ.pri.ə.si/
（措词的）不自然，不恰当
the fact that a word or phrase does not sound natural and is not acceptable when used in a particular situation
Native speakers have a general sense of the appropriacy and inappropriacy of language. 说母语的人对措词恰当与否大致有感觉。