Helvetisms (Neo-Latin Helvetia "Switzerland" and -ism) are features distinctive of the varieties of language spoken in Switzerland, most notably in Swiss Standard German, where they distinguish it from Standard German. The most frequent Helvetisms in German occur in vocabulary and pronunciation, but there are also some distinctive features in syntax and orthography. The French and Italian spoken in Switzerland have similar terms, which are also known as Helvetisms. Current French dictionaries, such as the Petit Larousse, include several hundred helvetisms.

The term Helvetism has also been used in broader cultural and historical contexts, particularly in reference to Swiss literary and intellectual currents from the 18th century onward. In this sense, it has denoted expressions of national identity and unity across linguistic and regional boundaries, often linked to movements emphasizing Swiss values, independence, and supracantonal solidarity.

The definitive work for German orthography, the Duden, explicitly declares a number of helvetisms as correct Standard German – albeit with the [schweiz.] annotation, denoting that the usage of the word is limited to Switzerland. However, not all words may be considered part of the "Swiss standard language"/"Swiss standard German" category, because frequency of usage must be evaluated as well; if this does not apply, or if a word's use is known to span only one or more specific dialectal regions, the word must be categorized "dialectal" (German: mundartlich, often abbreviated mdal.)

In orthographical terms, the most significant difference to Standard German outside Switzerland is the absence of ß (eszett). (After having been officially abandoned in the Canton of Zürich in 1935, this character gradually fell into disuse, until it was eventually dropped by the Neue Zürcher Zeitung in 1974.)

In everyday language, Helvetisms may be used both consciously and unconsciously by a Swiss German native speaker. Classic examples of Helvetism usage throughout entire literary works are found in a large part of Swiss literature, notably Jeremias Gotthelf's novels located in the Emmental; a contemporary example would be Tim Krohn in his Quatemberkinder. Another group, the most notable of whom is Peter Bichsel, deliberately use Helvetisms to arouse a sort of emotional attachment to the readers' home country: Bichsel is notorious for using dialectal words like Beiz (instead of Kneipe [English: "pub"]), or Kasten (instead of Schrank [English: "cupboard/cabinet/closet"]) in his "San Salvador" short story. Lastly, there is yet another group of authors whose readers are known to be located all over the German-speaking territory (Germany, Austria, Switzerland as well as some smaller minorities in other European countries) and therefore traditionally refrain from using any Helvetisms in their literary works.

In addition, words which are used outside Switzerland, but which originate from Swiss German may be called "Helvetisms".

Analogously to "Helvetisms", there are also Austricisms and Germanisms (also Teutonicisms).

In the area's cuisine, local culture and politics, there are numerous peculiarities that are not well known outside Switzerland and which do not have an equivalent standard German expression.