subgrade

American  

[suhb-greyd] / ˈsʌbˌgreɪd /

noun

1. 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.

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adjective

1. beneath the finished ground level of a project.

subgrade British  

/ ˈsʌbˌɡreɪd /

noun

1. the ground beneath a roadway or pavement

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Etymology

Origin of subgrade

First recorded in 1895–1900; sub- + grade

Example Sentences

See Examples For:

subgrade

“We use top quality ingredients. No discounts or subgrade meats. Fresh veggies. All the side dishes are prepared by our staff,” she says.

From Los Angeles Times ● Jul. 20, 2026

“Reinforcing the ground below the tracks required removing any work already completed, excavating additional soil beneath 1400 feet of track, and installing new subgrade materials to provide the required stability,” according to WMATA.

From Washington Times ● Oct. 1, 2022

Foundation.—The foundation or lower course consists of a layer of broken stone six inches thick placed on a well drained and thoroughly rolled earth subgrade.

From American Rural Highways by T. R. (Thomas Radford) Agg

If stored on the subgrade, a traction mixer is employed which is drawn along the road as the work progresses, the materials being placed directly in the mixer.

From American Rural Highways by T. R. (Thomas Radford) Agg

Wherever the subgrade soil is found unsuitable it should be removed and replaced with good material rolled to a bearing, i.e., so as to be smooth and compact.

From The Future of Road-making in America by Archer Bulter Hulbert