To gather information by direct observation rather than inference.

One or more observers in an area of interest.

(computing) In machine learning, the process of gathering objective (provable) data in order to test the system.

present participle of ground truth

Alternative form of ground zero

plural of ground-zero

Any meat that has been ground.

plural of ground rent

Synonym of air traffic control

(sports) a sports team's own ground, which is used for their home games. / (uncountable, figurative) an area or place where one feels familiar or at home.