1. Interjection (kandoushi)

   ah!; oh!; alas!

   occ. written as 嗚呼, 噫 or 嗟

   ああ悲しい。

2. yes; indeed; that is correct

3. aah; gah; argh

   in exasperation

4. hey!; yo!

5. uh huh; yeah yeah; right; gotcha

Also written あー、あぁ、ああっ、あ〜、あーっ、ああー、あ〜あ、あ〜っ、ああぁ、アー、アア、アァ