Falda is the traditional name in Mexico. Outside that tradition, butchers carry comparable beef cuts under different names — sometimes the same anatomical piece, sometimes a close cousin. The alternatives below are grouped by country so you can match what your local butcher actually carries.
Both are thin, flat cuts from the plate/flank area used in similar long-cooked Mexican preparations; skirt steak is the diaphragm muscle with more intense flavor, falda is the plate muscle and slightly milder.
Falda comes from the neighbouring plate region and is the most common Mexican substitute when suadero is unavailable.