noun a board which supports the back wen one is sitting;.
2. backboard ·noun a board serving as the back part of anything, as of a wagon.
3. backboard ·noun a board worn across the back to give erectness to the figure.
4. backboard ·noun a thin stuff used for the backs of framed pictures, mirrors, ·etc.
5. backboard ·noun a board attached to the rim of a water wheel to prevent the water from running off the floats or paddies into the interior of the wheel.