The literal meaning and implication is of some information transferred & handed down over time, orally, but that is not to say that something picked up in a book can't become traditional, especially as fiddle tunes are adapted to other instruments, say pipes, that require different phrasing, or note changes, which are then passed along to other pipers, and likewise, from singing to harp, or pipes to fiddle, etc. Tomás o Canainn makes a good point for music that 'sounds traditional' springing fully formed from the head of some musician or singer, and I think he's right. Another case should be made for people learning songs from recordings. That to me is tradition, the only difference being the musician is not physically present, but the action of transmission is similar, nothing beats learning a song from another person when you can ask questions, and hear the story, etc. but the tradition lives through recorded sources in my opinion. Now on to what is Folk music....