A papal cross is a cross having three crossbars. A schematic polyomino version of a papal cross is illustrated above.
Papal Cross
See also
Cross, Gaullist CrossExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Papal Cross." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PapalCross.html