Unicode (U+A66E): Singular-Use Multiocular-O-Symbol

Wieder was gelernt: Das Multiocular O (ꙮ, Unicode U+A66E) ist ein Symbol mit einer einzigen Verwendung, der Darstellung des „many-eyed seraphim“. (via JWZ)

Multiocular O (ꙮ) is a rare glyph variant of the Cyrillic letter O. This glyph variant can be found in certain manuscripts in the phrase «серафими многоꙮчитїи» ("many-eyed seraphim"). It was documented by Yefim Karsky from a copy of Psalms from around 1429, now found in the collection of the Trinity Lavra of St. Sergius, and subsequently incorporated into Unicode as character U+A66E.

Aus dem Unicode Proposal von 2007:

MONOCULAR O Ꙩꙩ, BINOCULAR O Ꙫꙫ, DOUBLE MONOCULAR Ꙭꙭ, and MULTIOCULAR O ꙮ are used in words which are based on the root for 'eye'. The first is used when the wordform is singular, as ꙩкꙩ; the second and third are used in the root for 'eye' when the wordform is dual, as Ꙫчи, ꙭчи; and the last in the epithet 'many-eyed' as in серафими многоꙮчитїи 'many-eyed seraphim'. It has no upper-case form.