soundpost
noun
music a small post, usually of pine, on guitars, violins, etc, that joins the front surface to the back, helps to support the bridge, and allows the whole body of the instrument to vibrate
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
Examples from the Web for soundpost
Historical Examples of soundpost
The soundpost must engage your closest attention, and must be of old Swiss pine.
Violin MakingWalter H. Mayson