a very thin board, as for the back of a picture.
Printing. a thin strip of wood used in justifying.
a thin sheet of wood used as veneer.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
British Dictionary definitions for scaleboard
a very thin piece of board, used for backing a picture, as a veneer, etc
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012