lower part of a shoji; base panel of a paper sliding door
Refers specifically to the solid lower section of a shoji screen, often made of wood, below the lattice and paper area.
The lower part of the shoji in the old house had many scratches.
Compound of 障子 (shoji, paper sliding door) and 腰 (koshi, waist/lower part), referring to the lower section of the door.