Meaning of “ground” - Learner’s Dictionary

ground

verb uk us /ɡraʊnd/
be grounded

If a vehicle that travels on water or in the air is grounded, it cannot or may not leave the ground:

The aircraft was grounded by fog.
be grounded in sth formal

to be based firmly on something:

Fiction should be grounded in reality.

(Definition of “ground verb” from the Cambridge Learner’s Dictionary © Cambridge University Press)