The surface of the Earth, as opposed to the sky or water or underground. / (uncountable) Terrain. / Soil, earth. / (countable) The bottom of a body of water. / Basis, foundation, groundwork, legwork.

simple past tense and past participle of grind

(US) To connect (an electrical conductor or device) to a ground. / (transitive) To punish, especially a child or teenager, by forcing them to stay at home and/or give up certain privileges.

Crushed, or reduced to small particles. / Processed by grinding.

Directly in an area of interest or active operations; in the field. / Used other than figuratively or idiomatically: see on, the, ground.

present participle of ground

Fundamental knowledge or background in a field or discipline. / The return to a fully conscious state after a psychedelic experience.

Dead and buried.

(sociology) Any theory that is based on observation of social phenomena

Of a person: having extensive knowledge of a subject. / Of an argument, etc.: based on good judgment and solid reasoning.