English. It was also used in medieval Scandinavia, but was later replaced with the digraph th, except in Iceland where it survives. The letter originated from the rune 'thorn' in the Elder Fuþark and was called thorn in the Anglo-Saxon and thorn or thurs (a category of beings in Germanic Paganism) in the Scandinavian rune poems. Its reconstructed Proto-Germanic name is Thurisaz.
It has the sound of either a voiceless dental fricative [θ], like th as in the English word thick, or a voiced dental fricative [ð], like th as in the English word "the". Modern Icelandic usage generally excludes the latter, which is instead represented with the letter eth <Ð, ð>; however, [ð] may occur as an allophone of /θ/, and written <þ>, when it appears in an unstressed pronoun or adverb after a voiced sound.