Flatbread is a wide name for bread that is thin and wide, not a puffy loaf you slice. Pitta, naan, tortillas, and the round base under a pizza all count. Some are cooked in a pan, some in a very hot oven; some use yeast and puff a little, some stay quite thin. You often tear it, wrap food in it, or use it as a plate. It is a kitchen word, not a scientific one — bakers and menus use it when they do not want to name one exact kind. Though actually it is not “one recipe”: if a shop says flatbread, you still need to ask which sort, because the word only tells you the shape.