Solecism

A solecism is any mistake or error which is felt to cause surprise, shock or outrage in the hearer, or embarrassment to the speaker. Solecisms can be committed in the fields of good manners or formal etiquette, or in language; or can even be “An error, incongruity, inconsistency, or impropriety of any kind” (OED).

It is a sign of the perceived importance of ‘correct’ language that the original meaning was “An impropriety or irregularity in speech or diction; a violation of the rules of grammar or syntax; properly, a faulty concord.” (The word is derived from a place, Soloi, the accent of whose inhabitants was felt to be offensive.)