n. An open field; a large open plain. Now champaign.n. The operations of an army during one season, or in a definite enterprise: as, the Vicksburg campaign.n. Continued or sustained aggressive operations directed to the accomplishment of some particular object: as, the temperance campaign; especially, in United States politics, organized action in influencing voters in an election, etc.: as, the last presidential campaign.n. In metallurgy, the time during which a furnace remains in operation without stoppage.To serve in a campaign.n. A more or less extended trip, excursion, or journey for a definite purpose, such as for botanizing or geologizing.