[suhb-greyd]Civil Engineering, Building Trades.


the prepared earth surface on which a pavement or the ballast of a railroad track is placed or upon which the foundation of a structure is built.


beneath the finished ground level of a project.

Origin of subgrade

First recorded in 1895–1900; sub- + grade Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for subgrade

Historical Examples of subgrade

British Dictionary definitions for subgrade



the ground beneath a roadway or pavement
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