Should "liquid" (easy to spend and trusted to be exchangeable for goods or services) be on that list? I wonder if it's generally left off because it's assumed, but BTC is not currently what I would consider "liquid;" the average time to confirm a transaction ranges from 30 minutes to (sometimes) over 16 hours [source: https://coincentral.com/how-long-do-bitcoin-transfers-take/]. So it's not a money I can spend on a pack of gum.

Contrast that with cash, checks, or credit cards, which generally clear in under a minute (checks being the notable exception, and indeed, the exception that makes them not always equivalently useful to the other two).