Square Back, Bergere 

A "Square Back Louis XVI Bergère" refers to a particular style of armchair that originated in France during the 18th century, specifically during the reign of King Louis XVI (hence the name).

A Bergère is a type of upholstered armchair with closed sides, often padded and covered with fabric. The Louis XVI style is characterized by its neoclassical design elements, which emerged during King Louis XVI's reign (1774–1792). This style is known for its straight lines, geometric shapes, and restrained ornamentation, drawing inspiration from ancient Greek and Roman architecture.

The "Square Back" designation likely refers to the shape of the chair's backrest, which could be square or rectangular in shape, rather than curved or rounded like some other styles of Bergères.

So, a "Square Back Louis XVI Bergère" would be an armchair with the characteristics of a Louis XVI style, including neoclassical design elements, paired with a square or rectangular backrest, adding a distinct visual element to the piece. These chairs are often considered elegant and refined, fitting well in formal or traditional interior design settings.