Old English used letters like thorn and eth that later disappeared and were replaced by the digraph th.

The longer version

Anglo-Saxon scribes had two letters for the sound we write as th: thorn, borrowed from the runic alphabet, and eth, a d with a crossbar. Both stood for the same pair of sounds, voiced and unvoiced, and writers chose between them by habit rather than by rule.

Printing ended them. Early presses used type cast on the continent, where neither letter existed, so printers substituted th, a digraph already known from Latin. Icelandic kept thorn and has kept it ever since, making it the main place modern readers meet the shape. Related losses include ash, wynn and yogh.

Where this entry sits

This category gathers small surprises about the English language, from odd spelling rules to words that quietly hide their own history. Expect palindromes, punctuation oddities, borrowed terms, and the strange ways writing systems record spoken speech. The full list sits on the Words and Language page, where every entry is listed in order.