ground level

ground level (countable and uncountable, plural ground levels)

1. (often attributive) The level of the ground, the surface of the earth.
2. The ground floor (of a building).

   Synonym: street level

3. (physics) Ground state, the stationary state of lowest energy of a particle.

• “ground level”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.