A sideboard is a piece of furniture that can be used for storing tableware and table linens, or for serving platters of food. That flat-topped cabinet in your dining room with a drawer full of cloth napkins? That's a sideboard.
Another word for a sideboard is a buffet. Not every dining room has one, but if your house has space, a sideboard can be a handy place to display your prettiest serving dishes or set out food at Thanksgiving so your guests can serve themselves. Sideboard gets its name from its traditional place, at one side of a dining room. This piece of furniture became popular in wealthy 18th and 19th century households.