The letters a, e, i, o, and u are vowels. All other letters are consonants.
A short vowel is the counterpart of a long vowel. So the “a” in gate is long while the “a” in bat is short.
Greek:
The letters α, ε, η, ι, ο, υ, and ω are vowels. See also diphthong.
- ε and ο are always short.
- η and ω are always long.
- α and ι can be either.
Hebrew:
Go here.