There are really two separate origins for
Fiona and therefore two separate pronunciations. The Irish name
Fiona (spelled Fíona in modern Irish Gaelic), was actually originally spelled Fíne and is from the Latin word
vinea, "vine", according to O Corrain & Maguire's
Irish Names. It is pronounced "Feena".
However, the Scottish name
Fiona is an invention of the 18th century author
James Macpherson. It was later made famous throughout Scotland when a man named
William Sharp (1855-1905)wrote popular novels under the pen name
Fiona Macleod. Most experts believe that Macpherson intended his name
Fiona to be a feminization of the word
fionn, meaning "fair, white". That
Fiona seems to have always been pronounced in three syllables, as "fee-OH-nuh".