EXPLANATION
There is a tendency in the English speaking world to claim mispronounced Greek words as being the correct pronunciation of those words. The only modern western nation which actually pronounces its Greek correctly is Norway. There are a number of Greek characters which when rendered into Latin characters for the English language are rendered by a convention which is wrong. Some such instances occur in the rendition of the character "K". For some reason it is usually rendered as the Latin "C", hence the northern English (who, though not Scots, refer to themselves  as "Scottish"), write "Celtic", instead of "Keltic" and mispronounce it "Seltic"(!).

The most contentious character in the Greek is the character "Y", ("ypsilon", which itself is miswritten as "upsilon" and mispronounced as "oopsilon").

(The "Y" character has anomalous properties in the English as well, evidence Year, mY, and maY.)

In its upper case form it is identical in appearance to the Latin "Y". In its lower case appearance it looks similar to the upper-case Latin "U". However, just because it looks like an upper case Latin "U" when rendered in its lower case form, does not mean it is pronounced so. Its pronunciation is actually dependant on whether it appears before or after another vowel, & what that vowel might be.

For some reason, Greek words which appear in the upper-case Greek as (for example) "ZEYS" are re-written in languages like Englsih as "zeus"(!) instead. To actually transcribe this word as it should be pronounced in English, it should appear as "Zevs".

The correct pronounciation of what in English is rendered "Zeus" is ZEVS. It is not, as is claimed in English glossaries, pronounced "zoows".

Greek "EY" = Latin EV (not eu);

Greek "AY" = Latin AV (not au);

The pronunciation of "Y" as "V" can be shown to have been so to at least c.270 BC. In the Septuagint translation of the Jewish Old Testament, from Hebrew to Greek, the word "Leviticus" for example is rendered with the "Y" character and thus appears as ΛΕΥΕΤΙΚΟΝ - which means that if it were transcribed today into Latin characters it would incorrectly appear as "Leuiticus".