(1) they are in widespread use as medium of exchange
(2) they serve as unit of account
(3) they are a stable store of value.
Most sovereign currencies fully meet all three criteria.
What about Bitcoin?
These criteria were built around the conventional currencies and bitcoin is not a conventional currency for sure. It is an innovation that shook all conventional thinking process on what a currency should be. So no, bitcoin doesn't meet all your criteria here. But bitcoin introduces new criteria on what a future currency system would look like.
(1) Decentralized - one world one currency
(2) International - No border restriction
(3) Fast - Bitcoin transactions are extremely faster when compared to any bank introduced international transaction
(4) Cheap - Cheaper than banking transactions
I don't think any conventional currency would meet these criteria when compared to bitcoin. That's the new generation currency system which will eventually be adopted by the entire world. Slowly but surely!