What salad ingredient is known as scallion in the US?

Scallions are a variety of young onions also referred to as green onions and spring onions. A scallion is made up of a white base that has not fully developed into a bulb and long green stalks that resemble chives. Both the white and the green parts are used in recipes and eaten both raw and cooked. Scallions are a member of the Allium family, which includes garlic, onions, leeks, and shallots.

Source: The Spruce Eats