Definition – What does Hard Currency mean?
Hard currency refers to a currency that is perceived as being stable by a majority of market participants. Generally speaking, a hard currency is wholly or partially backed by some durable good as in a gold standard or issued by a nation that is seen as having a strong economy and stable political system. Hard currency is also referred to as hard money.
ForexTerms explains Hard Currency
Traditionally, hard currency was only used to refer to gold-backed currencies. In modern times, however, very few currencies are 100% backed by gold. This means that the whole standard of hard currency has shifted to less literal measures like economic strength and political stability.