Sandwich (Σάντουιτς) is the general term, the catch-all Greek word for the bread-and-filling sandwich, and the model description says exactly that: the general term for bread sandwiches. This is the baseline, the everyday item a Greek bakery, kiosk, or café means when nothing more specific is named. It is not the gyro, not the souvlaki wrap, not a phyllo pie; it is sliced or split bread around cold fillings, the plain default against which the named regional sandwiches are variations.
The defining build is simple and worth stating because the rest of the catalog branches off it. A bread, sliced loaf, a soft roll, or a long sandwich roll, gets a fat layer to seal and carry flavor, often butter, a soft cheese, or mayonnaise; then a protein, commonly a sliced cured ham, turkey, or a hard cheese; then the fresh elements, tomato, lettuce, sometimes a pickle or olive. It is assembled cold and eaten as is, or pressed briefly in a tost press to warm and crisp it. Good execution is unglamorous and entirely about the basics. The bread should be fresh, fresh bread is the difference between a good plain sandwich and a sad one, and structured enough to hold its contents without going limp. The fat layer should reach the edges so no bite is dry. Tomato is the usual saboteur: salted and added too early, it weeps and turns the bread to paste, so a careful cook adds it last or drains it. Fillings should be in proportion, enough to satisfy without spilling. Sloppy execution is stale or squashed bread, a dry unbuttered edge, a soggy tomato-soaked middle, or a lopsided pile that falls apart on the first bite.
How it shifts is the entire rest of this section of the catalog: change the bread, the filling, the region, or apply heat, and you get a named variant. Pressed and toasted, it becomes a tost. Built with spiced cured meats and a warmer seasoning, it heads toward the Constantinople-style register. Loaded into three layers, it becomes a club. Filled with fritters or fish and wrapped in flatbread, it leaves the sliced-bread format entirely. Each of those, the tost, the regional styles, the wraps, deserves its own article rather than being crowded in here. Held to its plain definition, the Greek sandwich succeeds on the least glamorous terms there are: fresh bread, fat to the edges, fillings in proportion, and tomato that has not been allowed to ruin the bread.