Somewhere around this definition I found. The bill is a little dirty, and has some visible creases, but is still somewhat crisp. There are micro tears on the top, but nothing that stands out. Hope it helps.
Very Fine or (VF): Might have many folds, the note should still be crisp and has a very little amount of stains. There may be slight tears or very little holes but nothing that big, like half the bill missing.