The term "French bed" is often used in European countries to indicate not a specific type of bed, but merely a bed with a given mattress width. Called a "grand lit" in France, a French bed is one that is wider than a twin but narrower than a double. Also known as a "piazza e mezza" or one-and-a-half in Italy, such a bed is usually 48 inches wide and can hold one or two people --- provided the couple is willing to sleep very close together.
A French bed can also be a bed made in the traditional French style, rather than a mere width. These are beds made with high head and footboards, often of equal height. Almost always made of wood, the frame of the bed is often intricately carved with detailed scrollwork and floral motifs. French-style beds are much less common today than in the mid-19th century, when a bed was considered a significant piece of furniture.
Beds made in the French style can be easily confused with sleigh beds due to the high footboards and degree of craftsmanship. The best way to distinguish the two is to look at the shape of the headboard and footboard. French beds almost always have boards that extend straight upward while a sleigh bed features boards with a curved shape that imitates its namesake.
In Germany, a French bed has yet a third definition, dealing not with width or headboard-style but rather the construction of a mattress. Historically, a German double or matrimonial bed was made up of two twin mattresses pushed together with a small crack in between. Starting in the 1960s, this practice began to decline, giving way to single, wider mattresses in imitation of those Germans saw when vacationing in France. Thus, a German French bed is merely a double bed with a one-piece mattress.