pocket condo

(名詞) 面積非常小的公寓單位;樓層少的公寓大樓。condo = condominium (公寓大樓)。

So, what's the answer? As far as urban homes go, it might be a radical downsizing of condos and apartments. "Pocket condos" — or very small condos, under 550 square feet — have been around forever in New York City and are now showing up in many other major cities.
—Marnie Bennett, "Predicting the housing needs of Gen Y can be tricky," Ottawa Citizen, November 5, 2011

"It's getting very difficult to find good building sites in the downtown area," says Trinity-Spadina councillor Adam Vaughan. "So what you're now starting to see is projects pop out of there and onto main streets in other areas."

"The pocket condos are coming to a main street near you," he adds, referring to buildings between six and 10 storeys high.
—Sandro Contenta, "Battle over Ossington Ave. condo among several in city," The Toronto Star, July 7, 2012