Money

What do you think of when you think of the term ‘currency’ ? Dictionary.com offers these definitions of currency:
cur·ren·cy [kur-uhn-see, kuhr-] –noun, plural -cies.

1.
something that is used as a medium of exchange; money.

2.
general acceptance; prevalence; vogue.

3.
a time or period during which something is widely accepted and circulated.

4.
the fact or quality of being widely [...]