za (n.)

"a savoury dish of Italian origin, consisting of a base of dough, spread with a selection of such ingredients as olives, tomatoes, cheese, anchovies, etc., and baked in a very hot oven" [OED], 1931, from Italian pizza, originally "cake, tart, pie," a name of uncertain origin. The 1907 "Vocabolario Etimologico della Lingua Italiana" reports it is said to be from dialectal pinza "clamp" (from Latin pinsere "to pound, stamp"). Klein suggests a connection with Medieval Greek pitta "cake, pie" (see pita). Watkins says it is (perhaps via Langobardic) from a Germanic source akin to Old High German bizzo, pizzo "bite, morsel," from Proto-Germanic *biton- (see bit (n.1)). Ayto ["Diner's Dictionary"] seems inclined toward this explanation, too.

The notion of taking a flat piece of bread dough and baking it with a savoury topping is a widespread one and of long standing — the Armenians claim to have invented it, and certainly it was known to the ancient Greeks and Romans — but it is Italy, and particularly Naples, that has given its version of the dish to the world. ... Since then it has undergone a series of metamorphoses in base, topping, and general character that would make it hard for Neapolitans to recognize as their own, but which have transformed it into a key item on the international fast-food menu. [Ayto]

A pizza is manufactured, as far as I can ascertain, by garnishing a slab of reinforced asphalt paving with mucilage, whale-blubber and the skeletons of small fishes, baking same to the consistency of a rubber heel, and serving piping-hot with a dressing of molten lava. ["Simon Stylites," in The Bergen Evening Record, May 15, 1931]