Currency is a class of asset. A currency is an asset that maintains value, is highly liquid (fungible), and can serve as a unit of account. Of the three criteria, “real estate” as described by the OP only falls short in the third instance. Hence it is as “currency-like” as certain more traditional components of the monetary supply.

This is unusual since real estate is typically not very liquid, or at least wasn't considered to be liquid ‘enough’ and typically earns rates of return (net of maintenance) and had high opportunity costs (much how cigarettes in POW camps can only serve as currency if the prisoner decides not to actually smoke them, homes owned by those who dwell in them are not available for liquidation).

What real estate and currency have in common, both being asset classes, is that they're a store of value. Currency has other properties (medium of exchange, unit of account) that Real Estate does not. People aren't meaningfully trading real estate as a medium of exchange or using it as a unit of account. So it's not even close to a currency.

OP might mean that Real Estate has become a leading store of value, on par with currency, due to the factors he outlines.

Real estate is highly liquid? Compared to what?

You'd be hard pressed to find many economists (or other well-informed individuals) who would consider real estate a currency. Though at some point we're just debating semantics.

Edit: Also, real estate is extremely non-fungible, as individual instances of the asset class are not easily interchangeable.

And unless you have dozens or hundreds or thousands of acres, you can't subdivide it effectively. Let's say your property is worth $100,000. How do you get only $50,000 worth of value out of it? You have to sell the whole thing, do you then convert the remaining $50k to some other real estate? I suppose you can take out a second (third/fourth/fifth) mortgage on it for the desired value, but then you're stuck paying back that loan. So the property hasn't really provided you any direct value, just collateral to back your debts.

It's a value store, but hardly a currency.

Home equity loans, friend!

Exactly. The house/real estate isn't the currency, it's the asset backing the currency.

When we had the gold standard in the US, gold was not our currency. It was the asset backing our currency (strictly speaking, you weren't going to go into a corner store with $0.10 worth of gold to pay for your bottle of coke, though I suppose you could've). Gold is simply too impractical to use as the currency directly. You have to back something like that with certificates. IN the case of a commodity like gold it's easy to accumulate those certificates into an amount that's actually worth exchanging for raw gold. But with real estate? How am I going to practically claim 100 sq ft of prime lakeside real estate?

Quite amusingly the Weimar Republic quelled hyperinflation by rebasing the deflated currency on a limited asset... land. The new mark stabilised (until the Wall Street Crash, at least).

It is my understanding that vacancy rates have plunged and that a given property is never on the market for very long before a sale is achieved. This makes it unusually liquid for a real estate market.

Erm...

* QE was tremendously inflationary for all asset prices, including real estate prices which are not called "consumer prices" but it's not that easy to buy the argument behind it. Certainly for a lot of folks, real estate is their biggest expense, and it's very frightening to rent and not buy while housing prices go up all around you and you try to guess how far the cost of owning will become detached from the cost of renting. We can call people scared into buying overpriced houses "investors", but to me it's a bit of a stretch.

* Grandparent calls real estate, of all the asset classes inflated by QE, the new currency.

* You then, without agreeing with the grandparent, say QE isn't inflationary, as "understood" by many economists long ago. But if we stop calling houses "currency", is QE really not inflationary then? (I seriously don't think I fully understand it, BTW... So an honest question.)

Well we have to remember that when the stock market goes up 30% this year (or falls 30% this year) that's not inflation or deflation. That's a marketplace at work. Real estate is also an asset class that rises or falls. But those changes aren't inflation. That's market forces at work (supply and demand)