Marginal means existing at the edge or border of something, or so small that it barely matters.

In economics and business, marginal describes the tiny change that happens when you add just one more of something. If a bakery sells cookies for $2 each and it costs them $0.50 to make each additional cookie, that $0.50 is the marginal cost. The profit from selling one more cookie is the marginal benefit. These small changes might seem unimportant, but in business they add up: selling 1,000 extra cookies means $1,500 more profit.

In everyday language, something marginal is so minor it's almost not worth mentioning. If your grade improves by a marginal amount, it went up only slightly, maybe from 87% to 88%. A marginal improvement in your running speed might mean you finished the race just seconds faster.

The word also describes things pushed to the edges of society or attention. A marginalized group faces being pushed to the sidelines and treated as less important. Scientists might study marginal land that's barely suitable for farming because it's too dry, too rocky, or too remote.

Notice how marginal usually suggests something small, borderline, or barely significant, whether you're talking about money, measurements, or social position.