* 소년 (sonyeon): This is a general term for a boy, typically used for someone in their pre-teens or early teens. It's a more formal and neutral term.
* 남자아이 (namja ai): This literally translates to "male child," and is a more straightforward and widely applicable term for a young boy of any age.
* 꼬마 (kkoma): This means "little one" or "small child" and is suitable for a very young boy, perhaps a toddler or preschooler.
* 아이 (ai): This simply means "child" and can be used for a boy or girl, but often implies a younger age.
The best choice depends on the situation. If you're unsure, 남자아이 (namja ai) is a safe and generally understood option.