Webster Dictionary(0.00 / 0 votes)Rate this definition: 1  Hypo-. a prefix signifying a less quantity, or a low state or degree, of that denoted by the word with which it is joined, or position under or beneath. 2  Hypo-.
Confidence votes 25. St Patrick's Cathedral in New York City. ***Actually, the Basilica of the National Shrine of the Immaculate Conception in DC is larger than St. Patrick's in NYC. The National Shrine is the largest Roman Catholic church in the U.S., and one of the 10 largest Roman Catholic churches in the world.
Thatâs substantially larger than the next largest church in the world, St. Peterâs Basilica in Rome, which has a footprint of around 21,000 m^2. The Basilica is also the tallest Roman Catholic church in the world at 518 ft/158 m, and the second tallest Christian church in the world (second only by 12 ft/3.5 m!).