An alternative form of writing "meow", similar to the sound a cat supposedly makes. The term is usually spelled this way for a pinch of "cuteness" to any sentence - usually online.
I'm going to be a kitty today! "Miao~"
Pronounced mee-aow. A MIAO is a Mom I'd Approve Of. It is a socially acceptable way for a girlfriend or female friend to tell a guy that an older woman is bang worthy. It can be used in place of the word MILF.
Josh: OMFG did you see brian's mom at the pool yesterday? damn she is looking good!
Jenn: Indeed. She is totally a MIAO. I'd tap that.