Definition of a bedroom in Missouri

[Phillip Syrios]

Not really sure where to post this so if someone knows of a better forum let me know.

I have a house that has a forth bedroom in the basement with no windows and only one door into it, it looks very much like a bedroom but I know this would not qualify as a bedroom I can advertise and would have to call it a den or something like that.

My question is if I added a section door to the laundry area of the basement that leads to the garage would that could as having enough egress to let me count it as a bedroom? I can't seem to find any definitions of what constitutes as a bedroom in Missouri anywhere.