They are only synonyms to coinheads.
Cryptocurrency is just more commonly talked about than cryptography.
Calling cryptocurrencies crypto is like calling an MLM gig a job.
1) a person who secretly supports or adheres to a group, party, or belief.
2) cryptocurrency.
3) cryptography.
obvs the perceived meaning of words depends on context. You can't really just declare 3) is the only true meaning.
1. short for cryptography.
2. (informal) a person having a secret allegiance to a political creed, especially communism.
Or as a prefix / combining form:
1. concealed; secret.
From the Greek kruptos.
I have no idea who manages www.dictionary.com, but I honestly wouldn't be surprised if they took payments from coinheads to push this shit.