If it's a currency and is implemented using cryptographic concepts, I feel comfortable calling it a cryptocurrency. "Decentralization" is a spectrum and a highly subjective one, so I don't think it should be a requirement.
Indeed nowadays a lot of people relate the word 'crypto' with Blockchain related concepts, but being crypto only entails using some cryptographic concepts.
Cryptocommunication might be nothing but HTTPS/TLS. Cryptocurrency could very well be something similar, without involving Blockchain technology.
In that case I can say that I'm doing my groceries with a cryptocurrency, because the transaction is encrypted between the terminal and the bank. That doesn't make any sense.
