O (Mongolic)

O is a letter of related and vertically oriented alphabets used to write Mongolic and Tungusic languages.

Mongolian language

 * Transcribes Chakhar ; Khalkha, , and .  Transliterated into Cyrillic with the letter.
 * Indistinguishable from ', except when inferred by its placement: it is only found in medial or final syllables if the initial syllable also carries it, or rarely when it carries the vowel '.
 * = the final form used in loanwords, as in  (радио ).
 * = medial form used after the junction in a proper name compound.
 * Derived from Old Uyghur waw (𐽳), preceded by an aleph (𐽰) for isolate and initial forms.
 * Produced with W using the Windows Mongolian keyboard layout.
 * In the Mongolian Unicode block, ' comes after ' and before .