X-Frame - (Furniture) Vertical X-shaped frame; used on chairs and stools from the Middle Ages until the 17th century.

Xi - (Chinese) Chinese symbol representing happiness and longevity

X-Stretcher - (Furniture) Horizontal member between legs of a chair, table or stool in the form of an X.

Xylography - (Fine Art, Prints) an old term applied to wood-cuts and wood engravings.