Do you have any proposal in mind?
I'd say the best word to describe them is "public blockchains", because it leaves a lot of space for covering all the potential decentralized projects that utilize Bitcoin and some other coins, and it also takes back the word "blockchain" from bankers and governments who try to create a narrative that blockchain is some revolutionary technology that will improve those banks and governments.
I've heard other people saying that, but couldn't find the etymology of the word "cryptocurrency" myself, could you please provide some link if you have one? I'm very interested to learn about it!