O͘o͘ is one of the six Hokkienvowels as written in the Pe̍h-ōe-jī (POJ) orthography. It is pronounced [ɔ]. Because Hokkien is a tonal language, the standard letter without a diacritic represents the vowel in the first tone, and the other five possible tone categories require one of the following tonal symbols to be written above it:
Ó͘ ó͘ (second tone)
Ò͘ ò͘ (third tone)
Ô͘ ô͘ (fifth tone)
Ō͘ ō͘ (seventh tone)
O̍͘ o̍͘ (eighth tone)
History
The character was introduced by the Xiamen-based missionary Elihu Doty in the mid-nineteenth century, as a way to distinguish the Hokkien vowels /o/ and /ɔ/ (the former becoming ⟨o͘⟩).[1] Since then it has become established in the Pe̍h-ōe-jī orthography, with only occasional deviations early in its usage – one example being Carstairs Douglas's 1873 dictionary, where he replaced the ⟨o͘⟩ with an o with a curl (similar to that of the English Phonotypic Alphabet),[2] and a second example being Tan Siew Imm's 2016 dictionary of Penang Hokkien, where she replaced the ⟨o͘⟩ with ⟨ɵ⟩.[3]