Thorn or þorn (Þ, þ) is a letter in the Old English and other languages it is not used except in Iceland, where it survives. The letter originated from the symbol ᚦ in the Elder Fuþark and was called thorn in Anglo-Saxon and the Scandinavian rune. It is similar in appearance to the archaic Greek letter sho (ϸ), although the two are historically unrelated. The only language þ is still currently in use in is Icelandic.
It is pronounced similar to th as in the English word thick, or a sound similar to th as in the English word the. Modern Icelandic usage generally excludes the latter, which is instead represented with the letter eth.
The lowercase thorn character is unusual in that it has both an ascender and a descender.