(military) Actively engaged in fighting or dealing with the enemy; in battle or on maneuvers.
Away from the office, classroom, or laboratory; working with people or things in their natural environment.
In a real-world setting, as opposed to the controlled conditions of a laboratory or the hypothesized parameters of a theoretical approach.
Synonym: on the ground
Used other than figuratively or idiomatically: see in, field.
Source: en.wiktionary.orgThe commander in the field is always right and the rear echelon is wrong, unless proved otherwise. Colin Powell
Never in the field of human conflict was so much owed by so many to so few. Winston Churchill
I'm really convinced that our descendants a century or two from now will look back at us with the same pity that we have toward the people in the field of science two centuries ago. John Templeton
Children speak in the field what they hear in the house. Scottish Proverb
It is by the strength of their number that the ants in the field are able to carry their prey to the nest. Nigerian Proverb
Do not choose your wife at a dance, but in the field among the harvesters. Czech Proverb