Övdalian or Elfdalian (Elfdalian: övdalsk or övdalską, pronounced [ˈœvdɐlskãː]; Swedish: älvdalska or älvdalsmål) is a North Germanic language spoken by around 3,000 people who live or have grown up in the locality of Älvdalen (Övdaln), in the southeast of Älvdalen Municipality in northern Dalarna, Sweden.

Like all other modern North Germanic languages, Övdalian developed from Old Norse, a North Germanic language spoken by inhabitants of Scandinavia and their overseas settlements during the Viking Age until about 1300. It has developed in relative isolation since the Middle Ages and is considered to have remained closer to Old Norse than the other Dalecarlian dialects.

Traditionally regarded as a Swedish dialect, but by several criteria closer to West Scandinavian dialects, Övdalian is a separate language by the standard of mutual intelligibility. There is low mutual intelligibility between Swedish and Övdalian, but, since education and public administration in Älvdalen are conducted in Swedish, native speakers are bilingual and speak Swedish at a native level. People who speak Swedish as their sole native language, neither speaking nor understanding Övdalian, are also common in the area.

Övdalian belongs to the Northern branch/Upper Siljan branch of the Dalecarlian dialects or vernaculars, which in their turn evolved from Old Norse, from which Dalecarlian vernaculars might have split as early as in the eighth or ninth century, i.e., approximately when the North Germanic languages split into Western and Eastern branches. Övdalian (and other Dalecarlian language varieties) is traditionally placed among the East Scandinavian languages, together with Swedish and Danish, based on a number of features that Övdalian has in common with them. According to Lars Levander, some of the West Scandinavian features that simultaneously do occur in Övdalian are archaic traits that once were common in many Scandinavian dialects and have been preserved in the most conservative tongues east and west of Kölen. However, this is rebutted by Kroonen.

As of 2009, Övdalian had around 2,000 speakers and is in danger of language death. However, it is possible that it will receive an official status as a minority language in Sweden, which would entail numerous protections and encourage its use in schools and by writers and artists. The Swedish Parliament was due to address the issue in 2007, but has not yet done so. The Council of Europe has urged the Swedish government to reconsider the status of Övdalian on a total of five occasions. The Committee of Experts now encourages the Swedish authorities to investigate the status of Övdalian through an independent scientific study. In 2020, the Committee of Experts concluded that Övdalian fulfils the criteria of a Part II language, and asked the Swedish authorities to include reporting on Övdalian in its next periodical report as the language covered by Part II of the Charter, which the Swedish Ministry of Culture has not done in its 8th periodical report to the Council of Europe.

Ulum Dalska, The Organization for the Preservation of Övdalian, was established in 1984 with the aim of preserving and documenting the Övdalian language. In 2005, Ulum Dalska launched a process aimed at bringing about an official recognition of Övdalian as a language by the Swedish authorities.

Råðdjärum, The Övdalian Language Committee was established in August 2004 within Ulum Dalska, its first task being to create a new standard orthography for Övdalian. In March 2005, the new orthography created by Råðdjärum was accepted by the Ulum Dalska at their annual meeting. Råðdjärum consists of five permanent members: linguist Östen Dahl, dialectologist Gunnar Nyström, teacher Inga-Britt Petersson, linguist and coordinator of the committee Dr. Yair Sapir, and linguist Lars Steensland.

As an initiative from Ulum Dalska to encourage children to speak Övdalian, all school children in Älvdalen who finish the ninth grade and can prove that they can speak Övdalian receive a 6,000 Swedish krona stipend.