The iPhone Duo is Apple’s first foldable smartphone. The word “Duo” means “two” in Latin. But why is the product not called “Fold” or “Flip”? According to tech websites like Apple Insider, Apple wants people to focus on the dual-screen experience. However, names like “Fold” or “Flip” only show a mechanism (机械结构) or an action. Let's learn about other words that also mean “two”.