Yn
Yn is an archaic Cyrillic letter. It was an innovation entirely unique to the Romanian Cyrillic alphabet, not appearing in any other Cyrillic alphabet. It was derived from the Cyrillic glyph big yus.
It was used in the Romanian Cyrillic alphabet, where it represented the sounds,, and at the beginning of words. In the modern Romanian alphabet it is replaced by,, or.
It was used interchangeably with big yus up until the years 1683-1688 when it began to only be used in word initial position.