The spending cuts, meanwhile, are phased in gradually - which is why the "slope" metaphor makes more sense than the "cliff" one. It's not as though $1.2 trillion would suddenly disappear from the economy at the end of the year: The cuts, while undeniably significant, are set to be phased in over a decade. In addition, there are budgetary maneuvers that can be taken to at least somewhat soften the blow of both the tax hikes and spending cuts. (The Treasury Department could, for instance, freeze paycheck withholding levels.) Certainly, total inaction on the "fiscal cliff" over the long term would likely have a deeply negative impact on the economy. But if a deal comes in January or February, after the deadline - as it well could - the structural damage could be relatively small.

"We're not going to fall off the edge of the earth at the beginning of next year," said Ed Yardeni, president and chief investment strategist for institutional investor advisory Yardeni Research. "When you fall off a cliff you die. So it's a bit of an exaggeration to say that's what we're facing here."

What would happen on Jan. 2, when the fiscal measures are scheduled to kick in, without a deal? Most households facing higher taxes would see a relatively minor hit to their income. That could weaken demand and constrain spending in the short term, but it's unlikely to push the economy off some sort of proverbial ledge. And some of the tax increases wouldn't be felt for months. For instance, taxpayers newly subject to the alternative minimum tax, which tends to affect upper-income households, wouldn't pay those increased taxes until they file their returns in April.

For the broader economy, meanwhile, the incremental reduction in people's purchasing power would be far smaller than the full revenue increase the tax increase would generate over the entire year.

Many Democrats hate the "fiscal cliff" metaphor because they feel that they have more leverage to negotiate if the year-end deadline comes and goes without a deal. If and when taxes go up in January, Democrats would be in a position to put forth what is now a tax cut for 98 percent of Americans - and Republicans would face the prospect of opposing a major tax cut if they refuse the deal. (The GOP wants to extend the Bush-era tax cuts for the highest earners as well, something Mr. Obama strongly opposes.) The doomsday notion that America is poised to go off a cliff at the end of the year creates more pressure on Democrats to come to a deal before January, which would seem to help Republicans.

So which brilliant Republican operative came up with the "fiscal cliff" terminology? It wasn't an operative at all: The coinage appears to have come from Federal Reserve Chairman Ben Bernanke, who was re-nominated to his post by none other than Mr. Obama. Via Paul Waldman, here's Bernanke testifying to Congress in February: "Under current law, on January 1, 2013, there's going to be a massive fiscal cliff of large spending cuts and tax increases. I hope that Congress will look at that and figure out ways to achieve the same long-run fiscal improvement without having it all happen at one date."