Romansh ( roh-MA(H)NSH; sometimes also spelled Romansch and Rumantsch; Sursilvan: romontsch [ʁoˈmɔntʃ] (listen); Vallader, Surmiran, and Rumantsch Grischun: rumantsch [rʊˈmantʃ] (listen); Putèr: rumauntsch [rʊˈmɛntʃ] (listen); Sutsilvan: rumàntsch [rʊˈmantʃ], [rʊˈmaʊ̯ntʃ], [rəˈmœntʃ]; Jauer: [rʊˈmaʊ̯ntʃ]) is a Gallo-Romance language spoken predominantly in the Swiss canton of the Grisons (Graubünden). Romansh has been recognized as a national language of Switzerland since 1938, and as an official language in correspondence with Romansh-speaking citizens since 1996, along with German, French, and Italian. It also has official status in the canton of the Grisons alongside German and Italian and is used as the medium of instruction in schools in Romansh-speaking areas. It is sometimes grouped by linguists with Ladin and Friulian as the Rhaeto-Romance languages, though this is disputed.

Romansh is one of the descendant languages of the spoken Latin language of the Roman Empire, which by the 5th century AD replaced the Celtic and Raetic languages previously spoken in the area. Romansh retains a small number of words from these languages. Romansh has also been strongly influenced by German in vocabulary and morphosyntax. The language gradually retreated to its current area over the centuries, being replaced in other areas by Alemannic and Bavarian dialects. The earliest writing identified as Romansh dates from the 10th or 11th century, although major works did not appear until the 16th century, when several regional written varieties began to develop. During the 19th century the area where the language was spoken declined due to the industrialization of Switzerland, but the Romansh speakers had a literary revival and started a language movement dedicated to halting the decline of their language.

In the 2000 Swiss census, 35,095 people (of whom 27,038 live in the canton of the Grisons) indicated Romansh as the language of "best command", and 61,815 as a "regularly spoken" language. In 2010, Switzerland switched to a yearly system of assessment that uses a combination of municipal citizen records and a limited number of surveys.

In 2019, there were 40,074 Swiss residents who primarily spoke Romansh; in 2017, 28,698 inhabitants of the canton of the Grisons (14.7% of the population) used it as their main language.

Romansh is divided into five different regional dialect groups (Sursilvan, Vallader, Putèr, Surmiran, and Sutsilvan), each with its own standardized written language. In addition, a pan-regional variety called Rumantsch Grischun was introduced in 1982, which is controversial among Romansh speakers.