EDIT Usage in Medieval Nordic The “o ogonek” or “o caudata” is used in normalised Old Norse (i.e. Old Icelandic and Old Norwegian) orthography. It represents the U umlaut of /a/, and thus frequently occurs in inflected words with an /a/ in the stem, e.g. “spakr - spǫkum” (‘wise’), “land - lǫnd” (‘country’). The phonological value is that of a low, back, rounded vowel.

The character was in all likelihood modelled on the “e caudata” in Medieval Latin orthography when the Latin alphabet was introduced for the writing of the Nordic vernaculars in the 11th century. It frequently appears in Icelandic manuscripts, but only occasionally in Norwegian manuscripts (e.g. the Old Norwegian Book of homilies, AM 619 4to, around 1200).

There are many nicknames for this character. In Norwegian, it is usually referred to as “o med kvist”, ‘o with a twig’. While “o caudata” would probably be understood by most students, “o ogonek” is a rather esoteric name in a Nordic context.

The “o caudata” is no longer used in modern Nordic orthographies. It had phonemic status, and is usually rendered as /ǫ/, or sometimes as /ɔ/ (U+0254, the IPA symbol for its presumed pronunciation). In Icelandic, it merged with /ø/ in the 13th century and is now represented by the character “ö”. The development in Norwegian is more complex; it seems that it in some cases merged with /ø/ (e.g. “ǫl” > “øl”, ‘beer’) and in other cases with /o/ (e.g. “ǫsp” > “osp”, ‘aspen, populus tremula’).

Unlike the Polish ogonek, which goes all the way down to the bottom line (like “p”), the Old Norse ogonek should not be drawn much lower than a cedilla. As far as I know, there is no manuscript evidence nor any printed evidence of an Old Norse ogonek of the Polish type.

Two other characters with an ogonek may be found in Medieval Nordic sources. One is the “e ogonek” or “e caudata” (U+0119), which represents /æ/ (as in Medieval Latin). Another is the “a caudata” (U+0105), which frequently is found in transliterations of Runic inscriptions.