It's possible that you're thinking of one of these words:
* "Mafi" - This is the correct Arabic word for "there is not" or "there isn't." It is used in the negative form of the verb "to be."
* "Mafiish" - This is a colloquial form of "mafi" and is also commonly used to mean "there isn't" or "there is not."
* "Mafi hada" - This means "there is not this," or "there is no such thing."
If you can provide more context, I might be able to help you understand the intended meaning better.