backboard

• POS: Noun
• HYPHEN: back=board

CIDE DICTIONARY

backboard, n. [2d back, n. + board.].

•  A board which supports the back when one is sitting;  [1913 Webster]
•  A board serving as the back part of anything, as of a wagon.  [1913 Webster]
•  A thin stuff used for the backs of framed pictures, mirrors, etc.  [1913 Webster]
•  A board attached to the rim of a water wheel to prevent the water from running off the floats or paddles into the interior of the wheel.  W. Nicholson.  [1913 Webster]
•  A board worn across the back to give erectness to the figure.  Thackeray.  [1913 Webster]

OXFORD DICTIONARY

backboard, n.
1 a board worn to support or straighten the back.
2 a board placed at or forming the back of anything.