Feel free to redefine "sound money" to take into account bitcoin.
Redefine it from what?
But honestly, I don't hear the phrase "sound money" that much, where do you keep hearing it?
Really? Do you only read mainstream media finance articles?
The phrase is used a lot in the Daily Reckoning for example:
http://dailyreckoning.com/why-the-feds-really-hate-sound-money/