Is 2-multiset a valid term?

Question

I am trying to describe the edges of an undirected graph that contains loops. On Wikipedia they are characterized as 2-multisets, meaning it has two elements which can be identical, and the order is not important. I never heard of that term, and find no reference to it anywhere else, so I am not sure whether it is OK to use it in my thesis. Can anyone clear that up for me?

Answer 1

Yes. See the Wikipedia article on multisets and the many references therein for where it has occurred previously in literature.

(Note, in the context, a 2-multiset merely means a multiset containing 2 elements.)

Answer 2

As Willie Wong notes, it's a perfectly valid term, but at least I personally would find "unordered pair" more natural than "2-multiset".