An open jaw is when you fly back to your original departure city from someplace other than the airport you flew to first. For example, if I fly outbound DTW-LAX, and come home SFO-DTW. Somehow I have to get myself from LA to San Fran, on my own dime.

I think with multiple stops as you mentioned, you would be looking for a circle trip. That is, if you want all your flights to be on a single ticket. You can always book one ticket to say Chicago, and then do separate flights from there to MSP and SEA.