Small green oranges are often referred to as unripe or immature oranges. Oranges, like many citrus fruits, change color as they ripen, transitioning from green to yellow or orange.
It's important to note that if you purchase green oranges, you can allow them to ripen at room temperature. Placing them in a bowl with other ripening fruits, such as bananas, can expedite the process. While unripe oranges may not be as sweet as fully ripened ones, they can still be used creatively in various culinary applications.