two slices of usu buttered bread containing any of various fillings, e.g. cold meat, cheese, or jam
Professor McGonagall raised her wand … A large plate of sandwiches, two silver goblets and a jug of iced pumpkin juice appeared with a pop — J K Rowling
a sponge cake with jam, cream, etc between its two or more layers
something resembling a sandwich in being layered or having a filling
[named after John Montagu, fourth Earl of Sandwich d.1792, for whom this snack was devised so that he could eat without leaving the gambling table]