The above is my attempt at the world's shortest riddle.
EDIT - 23 Aug 2015
Here is my bid to get the riddle re-opened. Naturally to satisfy the community I have to add other constraints outside of the four words and this may make the riddle less likely to be the shortest. However, even if my riddle isn't the shortest, I'm still posing the question and looking for an answer.
The answer is a single 8-letter word.
The answer contains four vowels. It begins with a vowel and ends with a vowel.
Each line of the riddle must individually and independently fit the answer.
You must convincingly explain how the answer precisely fulfils the clues (in a normal riddlish fashion), possibly with the use of dictionary definitions.