Omega.
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Omega (Ωω) and Omicron (Oo). Both sound like o nowdays.
you can use the word an if the word after it begins with a vowel
No, a combining vowel is used when the suffix begins with a vowel.
The word "banned" begins with a vowel sound and rhymes with stand.
An evergreen tree. If the word begins in a vowel or consonant with a vowel sound, it is preceded by "an". If the word begins with a regular consonant, it begins with "a".
The question doesn't make sense. A "vowel" is only one letter. So the question is asking "What one Greek letter begins with e?" I think the word you're looking for is epsilon, the fifth letter of the Greek alphabet.
omicron
greek
if the word after it begins in a vowel
Yes. The A is a long A sound, as in sale and pale. The E is silent.
The article "an" is used before a word when the word begins with a vowel. "A" is used when the word begins with a consonant. The exceptions are when the word begins with a consonant but it sounds like a vowel, or when it begins with a vowel but it sounds like a consonant. There are very few exceptions. And I cannot think of one at the moment.
asthma
Iota