Thula (/ˈθuːlə/; pl. thulas, from Old Norse: þula pl. þulur), is the name of an ancient poetic genre in the Germanic literatures (but see below). Thulas are metrical name-lists or lists of poetic synonyms compiled, mainly, for oral recitation. The main function of thulas is thought to be mnemonic. The Old Norse term was first applied to an English poem, the Old English Widsith, by Andreas Heusler and Wilhelm Ranisch in 1903.Thulas occur as parts of longer poems, too; Old Norse examples are found in various passages of the poetic and the prose Edda (esp. Skáldskaparmál with the Nafnaþulur, Grímnismál, Alvíssmál), the Rígsþula as well as in the Völuspá. Thulas can be considered as sources of once canonic knowledge, rooted in prehistoric beliefs and rituals. They generally preserve mythological and cosmogonical knowledge, often proper names and toponyms, but also the names of semi-legendary or historical persons. Their language is usually highly formalized, and they make extensive use of mnemonic devices such as alliteration. For a number of archaic words and formulas some thulas are the only available source. The term and the genre may go back to the function of the Thyle (Old Norse: þulr), who held the function of an orator and was responsible for the cultus.