A sound of moaning. To express your disdain for something another person just said, mostly if it's targeted at yourself or if you don't like it. Note: can be in a positive way, too (to show that you like something).
Mostly used in internet relay chat, although possible under other circumstances. Can also be found in an ironical way, where someone uses "moah" to tease people who actually use it all the time.
Bert: it can be found on page 1267 of the book.
Ely: moah, I surely don't look at this myself! Give me a summary!
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Vish: maybe ely is more in touch with these kinds of things... :P
Ely: moah -.-
moah is a beautiful girl who deserves the world. she is absolutely stunning and better than anyone else. She is way out of your league and will get all the guys. I agree that moahs are the best and i wish i knew one. Stunning, perfect shes better than heather