Well, there's an efficiency argument related to holding onto cash instead of investing. That is, holding onto large quantities of cash and not investing means

Well, there's an efficiency argument related to holding onto cash instead of investing. That is, holding onto large quantities of cash and not investing means losing out on returns. The only time that's rational is if there's significant market risk, or if you get better returns due to appreciation in currency value (which amounts to treating money like a commodity/investment). So, I'd argue that holding onto large quantities of money in lieu of allowing it to circulate due to fears does qualify as "hoarding", insofar as the money could be put to better, more productive use while the person holding onto the cash may be losing out on potential upside. The term is particularly apt when there are concerns of a deflationary spiral, as cash hoarding truly does become a problem in that circumstance.