A word used for somebody that is seems to be a very nice and innocent person, but is actually a huge back-stabber. Beware of Mamoonas.
Person 1: Yo, I really thought that chick was my friend, but then she goes and ignores me for months. She was probably just using me for homework answers.
Person 2: Dang, she's such a Mamoona.
Person 2: Dang, she's such a Mamoona.
by yuhhhhhhhhhhhhh October 19, 2019
