Lasagna (singular, in Italian; plural lasagne pronounced [laˈzaɲe]) is both a form of pasta in sheets (sometimes rippled, though seldom so in Northern Italy) and also a dish, sometimes named lasagne al forno (meaning "oven-cooked lasagne") made with alternate layers of pasta, cheese, and often ragù (a meat sauce) or tomato sauce. In Italy the dish is called "Lasagne" and not "Lasagna".
The word lasagna, which originally applied to a cooking pot, now simply describes the food itself. Most English-speaking people follow the Italian usage and use the plural "lasagne" to refer to both the dish and the pasta, but Americans commonly use the singular "lasagna".
Many recipes call for several kinds of cheese, most often ricotta and mozzarella. Mozzarella is made in the south of Italy, so the use of these two cheeses is typical of lasagne made in Naples or further south.
Lasagne alla Bolognese uses only Parmigiano Reggiano, Bolognese sauce and nutmeg flavored béchamel sauce (besciamella). Classic Bologna lasagne should be made with Lasagne verde (green lasagne) which is egg pasta with added spinach, although in other towns of Emilia-Romagna, the lasagne need not be green.
There are hundreds lasagna variants, from artichoke spinach lasagna to spicy chipotle lasagna to vegetarian and seafood versions. The dish lends itself to creative use of ingredients by home cooks as well as the chef.
Łazanki is a similar dish made in eastern Europe.
Although the dish is generally believed to have originated in Italy, the word "lasagna" comes from the Greek λάσανα (lasana) or λάσανον (lasanon) meaning "trivet or stand for a pot", "chamber pot. The Romans borrowed the word as "lasanum", in Latin, meaning "cooking pot". The Italians used the word to refer to the dish in which lasagna is made. It wasn't long before the name of the food took on the name of the serving dish.
Another theory suggests that lasagna might come from Greek λάγανον (laganon), a flat sheet of pasta dough cut into strips.
The recipe was featured in the first cookbook ever written in England, leading to an urban legend that the dish originated in the British Isles. The claim is dubious, in light of the much earlier Roman use of "lasanum".