The surname Chariatti (and its many variants recorded in Argentina as Chariatte, Chariati, Chariate, Chariato, Charriat, Charitte, among others) is the Argentinized spelling of a surname of Swiss-Romand origin, coming from the canton of Valais, in French-speaking Switzerland. This emerges from the analysis of parish, civil and military records of Argentina.

This surname does not figure in the studies of Italian surnames, nor in the dictionaries of French surnames consulted, so that its etymology must be considered indicative in lexicographic terms, although solid from the documentary and migratory point of view.

When one speaks of "Swiss-Romand" one refers to the population of the so-called Romandy, that is, the western region of the country where the predominant language is French. The term romand comes from roman, in the sense of Romance languages derived from Latin. This zone includes cantons such as Geneva, Vaud, Neuchâtel, Jura and part of Valais. In the case of Valais, it is a bilingual canton, where French-speaking (Romand) and German-speaking areas coexist, which is relevant for understanding the historical variability of the surnames of the region.

The origin of the surname is linked directly with the place name Charrat, a former commune of the district of Martigny, documented by Swiss historiography since 1315 under the form Charas. This locality, situated in the Lower Valais, functioned as an autonomous entity until its merger with Martigny in 2021. In onomastic terms, the surname is clearly toponymic of provenance, since it originally designated the person native to Charrat or the family residing in that locality.

From the linguistic point of view, the regional French of Valais introduces a central element for understanding its evolution. The digraph ch is pronounced as sh, so that Charrat was realised approximately as sha-rá, with the final t silent. However, the canton of Valais is not homogeneously French-speaking, and this historical coexistence with German-speaking areas, added to the distance between European orthographic systems, generated a strong variability in the perception of the surname outside Switzerland.

When the families arrived at the Río de la Plata, this phonetic form clashed with two different systems: Rioplatense Spanish, where ch is pronounced as /tʃ/, and Italian, where ch before e or i is pronounced /k/ and the sequence cha does not naturally exist as a direct correspondence. This triple phonetic and orthographic tension produced a great instability in the written fixing of the surname.

In Argentine parish and civil records of the end of the 19th century there is documented, within one same family unit arrived in the partido of La Ensenada (province of Buenos Aires), a notable multiplication of spellings, among them: Chariatte (original reference form), Chariati, Chariate, Chariato, Charitte, Charriat, Chearete, Hariate, Harriate, Sariat, Sariati, Saryati and Shariati. This variation does not respond to internal changes of the surname, but to the way in which different registry agents reinterpreted one same foreign pronunciation.

Within this set different processes of adaptation can be identified: some forms reflect a graphic Italianization (Chariati, Chariate), others a phonetic Hispanization with loss or transformation of the initial segment (Sariat, Hariate), and others attempts at approximation to the French form (Charriat). In this sense, the genealogical reconstruction requires considering all these variants as expressions of one same documentary root.

As a whole, the case of Chariat shows how a surname originated in a French-speaking region of Valais can acquire an Italian or Hispanic appearance in the records of the Río de la Plata, not by change of origin, but through the interaction between different phonetic systems, administrative writing practices and processes of migratory adaptation.