Interjection

1. A cry of fright, distress etc.
2. Used within the British Army in response to an answer to an obvious question. This is a question that you have set the other person up to answer. Can become quite frustrating as you become paranoid answering any question in case it is a Wah!

   Steve: "Is that a can of beer in your hand Bill?"

   Bill: "Yeah!"

   Steve: "Wah!"

   Bill: "Bugger, been Wah'd again!"