to correct the OP
currency is anything used as a medium of exchange
That's not correct!
Currency is not ANYTHING used as a medium of exchange, you can use many things as a medium of exchange which I'm sure is obvious around you. You can purchase your shoe and other products and properties with gold or other products and properties, which makes your definition faulty.
Currency is rather a LEGAL TENDER (fiat) note and others backed by the central bank of a country.
currency is a broad term...
then within the term there are different types of currency
there are many types of currency.
money is the "legal tender" subcategory of currency.. not the other way round
bitcoin does have its own community and association that xBTC is worth $yyyyy
bitcoin is not the money of US central bank. the US central bank just sees bitcoin as an asset currency
bitcoin is OUR money