Eth // (capital Ð, small ð; also spelled edh or eð) is a letter used in Old English, Icelandic, Faroese (in which it is called edd), and Elfdalian. It was also used in Scandinavia during the Middle Ages, but was subsequently replaced with dh and later d. Its use has survived in Iceland and the Faroe Islands. The capital eth resembles a D with a line through the vertical stroke. The lower case resembles an insular d with a line through the top. The lower-case letter has been adopted to represent a voiced dental fricative in the IPA.
In Icelandic, ð represents a voiced dental fricative like th in English "them", but it never appears as the first letter of a word. The name of the letter is pronounced [ɛθ]; i.e., voiceless, unless followed by a vowel. It has also been labeled an "interdental fricative".
In Faroese, ð is not assigned to any particular phoneme and appears mostly for etymological reasons; however, it does show where most of the Faroese glides are, and when the ð is before r it is, in a few words, pronounced [ɡ]. In the Icelandic and Faroese alphabets, ð follows d.
In Old English, ð (referred to as ðæt by the Anglo-Saxons) was used interchangeably with þ (thorn) to represent either voiced or voiceless dental fricatives. The letter ð was used throughout the Anglo-Saxon era, but gradually fell out of use in Middle English, practically disappearing altogether by 1300; þ survived longer, ultimately being replaced by the modern digraph th.
Lower-case eth is used as a symbol in the International Phonetic Alphabet (IPA), again for a voiced dental fricative, and in IPA usage, the name of the symbol is pronounced with the same voiced sound, as /ɛð/. (The IPA symbol for the voiceless dental fricative is θ.)
Computer input 
|Unicode||U+00D0||U+00F0||Inherited from the older ISO 8859-1 standard|
|Unix-like||Compose key plus D and H||Compose key plus d and h||For ISO-8859-1- and UTF-8-based locales|
|Faroese keyboard||Ð||ð||can be typed directly|
|Icelandic keyboard||Ð||ð||can be typed directly|
|Mac OS X||Shift+Option+D||Option+d||Typed by activating the US Extended keyboard layout|
|Microsoft Windows||Alt key 0208||Alt key 0240||AltGr+d with the US International keyboard layout|
- The letter ð is sometimes used in mathematics and engineering textbooks as a symbol for a spin-weighted partial derivative. This operator gives rise to spin-weighted spherical harmonics.
- The modern Greek letter delta (Δ, δ) has, in general, the same phonetic value, and ð is the only Latin alphabet letter faithfully representing delta's phonetic value. (In Ancient Greek, delta represented a d sound.)
- The symbol is mentioned in the Rush song "By-Tor and the Snow Dog" in the first verse:
Prince By-Tor takes the cavern to the North light,
The sign of Eth is rising in the air.
See also 
Notes and references 
- Freeborn, Dennis (1992), From Old English to Standard English, London: Macmillan, p. 24.
- "Eth", American Heritage Dictionary, Dictionary, Reference.
- David Wilton (September 30, 2007). "Old English Alphabet". Word origins. Retrieved 22 August 2010.
- Example of Welsh text interchanging eth with dd, UK: CAM.
|Wikimedia Commons has media related to: Ð|
|Look up eth in Wiktionary, the free dictionary.|
- "Thorn and eth: how to get them right", Operinan, Briem.
- "Alvdalsk ortografi" (PDF), Förslag till en enhetlig stavning för älvdalska (in Swedish), SE, March, 2005.