Is that a bolsa or a bolso?

I have been looking for a new bag for a long time, and this last weekend I finally spotted one that I liked, so I bought it. Now the tricky part. Is it un bolso or una bolsa? This has been one of those facts that lives in my head and pops out a different answer each time I have to refer to any type of bag.

To put it finally to rest here is the definitive definition.

Bolso or bolsa?

When to use una bolsa or un bolso.

A bag (such as a messenger bag) is una bolsa.
A woman’s handbag is un bolso.
A plastic bag from the supermarket is una bolsa.
A back pack is una mochila

I think it was the masculine/feminine cross over with the men’s and women’s bags that had me confused. Now it is written down in my study notebook, I will never get it wrong again. Plus, I have a nice new bag.