Rioplatense Spanish (/ˌriːoʊpləˈtɛnseɪ/ REE-oh-plə-TEN-say, Spanish: [ˌrioplaˈtense]), also known as Rioplatense Castilian or River Plate Spanish, is a variety of Spanish originating in and around the Río de la Plata Basin, and now spoken throughout most of Argentina and Uruguay. This dialect is widely recognized throughout the Hispanosphere due to its strong influence from Italian languages, a result of significant historical Italian immigration to the region. As a consequence, it has incorporated numerous Italian loanwords—giving rise to the lunfardo argot—and is spoken with an intonation similar to that of the Neapolitan language from Southern Italy.
It is the most prominent dialect to employ voseo (the use of vos in place of the pronoun tú, along with special accompanying conjugations) in both speech and writing. Many features of Rioplatense Spanish are also shared with the varieties spoken in south and eastern Bolivia, as well as in Paraguay, particularly in regions bordering Argentina. It also strongly influences the fronteiriço, a pidgin spoken in Uruguay's border regions with Brazil, as a result of continuous interaction between the communities of both nations.