Uk (Ѹ ѹ; italics: Ѹ ѹ) is a digraph of the early Cyrillic alphabet of the letters О and У although commonly considered and used as a single letter. To save space, it was often written as a vertical ligature (Ꙋ ꙋ), called "monograph Uk". In modern times, ⟨оу⟩ has been replaced by the simple ⟨у⟩.
Ѹ is romanized as U, Ꙋ is romanized as Ū.[1]