The principal official languages (German, French, and Italian) have terms, not used outside of Switzerland, known as Helvetisms. German Helvetisms are, roughly speaking, a large group of words typical of Swiss Standard German, which do not appear either in Standard German, nor in other German dialects. These include terms from Switzerland's surrounding language cultures (German Billette from French), from similar term in another language (Italian azione used not only as act but also as discount from German Aktion). The French spoken in Switzerland has similar terms, which are equally known as Helvetisms. The most frequent characteristics of Helvetisms are in vocabulary, phrases, and pronunciation, but certain Helvetisms denote themselves as special in syntax and orthography likewise. Duden, one of the prescriptive sources for Standard German, is aware of about 3000 Helvetisms. Current French dictionaries, such as the Petit Larousse, include several hundred Helvetisms.

What are terms that are not used outside of Switzerland known as?