‘Grade’ is a term used to describe the level of the earth at a specific location or at ground level. In construction, the terms ‘above grade’ and ‘below grade’ can be used respectively to describe the portion of a building that is above or below the ground. In tunnelling, the invert of a tunnel may be described as being 25m below grade or ground level.

https://www.designingbuildings.co.uk/wiki/At_grade#:~:text=&...

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Note added at 44 mins (2022-09-04 16:59:28 GMT)
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