þorn

Thorn (Þ, þ) is a letter of the Latin alphabet once used in Old English and Icelandic to represent the dental fricatives /θ/ and /ð/. Its name comes from Old English þorn, meaning thorn, and the letter itself is usually treated as a distinct character in historical orthography. In encoding systems it is represented by the two code points U+00DE (Þ) and U+00FE (þ).

In Old English, thorn could denote either /θ/ as in thin or /ð/ as in this, with the exact value often determined by context. Beginning in the late medieval period, English printers increasingly replaced thorn with the digraph “th,” and by the 15th century thorn disappeared from most English texts. In Icelandic, however, þ remains in standard use today for the voiceless /θ/ sound, while the voiced /ð/ is written with the letter ð (eth).

The shift away from thorn in English gave rise to several typographic and orthographic quirks. A common, widely repeated explanation is that the famous “ye” in phrases such as “ye olde shoppe” comes from thorn being substituted by the letter y; in reality the form arose from printers’ use of a thorn-like character and later misinterpretations, but the story has become part of popular lore.

Today thorn survives as a living letter in Icelandic and as a historical orthographic symbol in studies of Old English and medieval manuscripts. It is encoded in Unicode and can be represented in digital text as Þ (uppercase) or þ (lowercase).