[MaulingMonkey]

In the context of currency, "backing" is typically understood to be referring to guarantees, typically by a government or bank, such as the gold standard: "ensuring" value by "guaranteeing" some conversion rate to something else, especially something else considered to have some "intrinsic" value, to stabilize the value of the currency.

This is of course a fuzzy line. And you're right, there are other definitions of "backing" which render it a meaningless term. But the distinction is a useful one for discussing these matters, so what terminology would you prefer instead?