Can't resist joining in this one.

I think that a song is 'Folk' if people are singing it independently of any commercial, government or academic patronage.

I should really have written ...PEOPLE ARE SINGING IT... because that is the important thing.

I know that this definition might exclude a lot of 'traditional' songs that exists in standard archived collections, but if people don't sing them any more then I don't think that they are really songs, just archived representations.
Now if you are one of those people that disagree with this, don't come back and complain to me about definitions. Get out there and SING THOSE SONGS and I'll be the first to applaud.

Then there is all that Singer/Songwriter stuff that is passed off as folk music. Not that I am against Singer/Songwriters (I'm one myself) but if the S/S is the only person who sings his/her songs then they are not folk songs. Should they be lucky enough that a lot of other people would start singing, and keep on singing, them then they would become 'folk'.
So keep singing, and keep on submitting songs to DT so that we can share them ,

Bert.