From Richmond Folk Music website -
"Most traditional music enthusiasts would define "traditional" folk music as songs and tunes which have been handed down through several generations, and which have no known author. This is what sets traditional music apart from "folk" or "acoustic" music, which could include very modern material that may not sound traditional at all. Traditional songs often tell stories and vocals may sometimes be sung unaccompanied. The beauty of traditional music is that it has been honed over the years by countless singers and musicians, all of whom have left their mark on the song or tune. "

I'm sorry, but your definition tells me ver little about what to expect. From the standpoint of a person who is going to decide to buy a CD or attend a festival, your description tells me very little. It is the same with using the words "opera" or "rap" - it says very little about what the music is - unless you have a stereotype in your mind about what the music is.   Opera and rap are just as diverse as folk.

But that is the whole damn point! You do not need to tell me more! Folk music is not like buying a box of cereal where you need to read the ingredients to find out how much salt, nuts or fiber is contained.