Manar means to flow or to pour forth. The idea is that it is something that comes out quickly like to gush. Figuratively it means to abound.
A friend of mine used manar last week while he was teaching a class. I have never heard the word used that I can remember outside of this reference, but it seems like it is a handy word to add to the vocabulary. I will try to use manar and see if I get any strange looks.