TITLE: Backwards epsilon
QUESTION [39 upvotes]: What does the $\ni$ (backwards element of) symbol mean?  It doesn't appear in the Wikipedia list of mathematical symbols, and a Google search for "backwards element of" or "backwards epsilon" turns up contradictory (or unreliable) information.
It seems it can mean both "such that", or "contains as an element".  Is this correct, and if so, which is the more common usage?

REPLY [6 votes]: The fact that \ni is \in written in the opposite direction, should also support the idea of those who think that this symbol means "contains as an element".