"different people mean different things when the term 'folk music ' comes up."
Doesn't matter what people make it mean Al - unless they have a consensus on what theyy think it means, it means what it means - folk = belonging to 'the folk sun, played, and probably made by them - that is what it has been documented as when applied to song, music, dancing storytelling, lore.... and any other related discipline.
couple it with traditional (as it should be) and you have the people's music that has been passed through a process, adapted, changed to suit wherever it lands   
Far from it being "exclusive" it is the most democratic, publicly owned art form there is - it belongs to 'the folk', 'the common people' - 'the masses' -or rather - it belongs to nobody
We use anguage to communicate with each other - if we decide words mean whatever somebody wants them to mean we stop talking to each other
What do you think would happen if you suddenlt decided you wanted to call the music you perform 'jazz' or 'classical' - or 'chamber music' - or hip-hop'...?
I reckon you'd find yourself on a trades description charge
Why should folk be any different - that's the label that was stuck on our product in 1846 - it's our logo
Jim