Why is the "ph" pronounced like a "v" in "Stephen"? Is this the only word like that?

Solution 1:

The source of Stephen is the Greek name Stephanos. This name was borrowed into English long enough ago that the intervocalic [f] sound was voiced to become [v]. This is a regular sound change that was also responsible for some other f~v alternations in English, such as loaf~loaves. However, in the name Stephen the spelling "ph" remained (or has been restored) due to the influence of the Greek original. In other words, Stephen and Steven are pronounced the same way, but the former has an anachronistic spelling.

Solution 2:

I always found interesting that both "phial" and "vial" exist in English, having a common origin but different pronunciations. OED lists "vial" as an alteration of "phial"; the "ph" is originally Greek.

Does this count?

Solution 3:

Is there any other instance of "ph" being pronounced as "v" in either American or British English?

In British English, nephew can be pronounced nev-yoo.

Solution 4:

Stephen is of Greek origin (Stephanos). The ph is unusual in its v pronunciation. The only possibility I can think of is that it arrived in English via Spanish, where it is spelt 'Esteban'. The Spanish pronunciation of 'b' is somewhere between English 'V' and 'B'. In Hungarian it is spelt 'Istvan', so there's another possible source.

Solution 5:

Born in London, I have always pronounced nephew with a 'v' sound. Locals in Essex (England) also pronounce the village name of Bulphan as 'Bulvan' rather than 'Bulfan', even though the second syllable is derived from the word fen.