Maknae (막내) is the youngest member of a family or a group. The definition of this term is further expanded on the Kimchi Cloud website:

In Korean culture, age is deemed an important factor in almost all areas of life. Generally speaking, the older you are, the better. (Of course excluding the small fact that the older you get, the closer to death you also get.) This is because in Korean, China and Japan among other Asian countries heavily influenced by confucianism, juniors are expected to show reverence to their seniors.

This also applies to life in school. For example, if someone entered university before you, you, the hoobae (in Hangul: 후배) have to show them, the seonbae (선배) respect and you are, in a sense, considered “lower” than them. The true nature of this type of interaction and relationship is of course much more complex than this and it’s not like the older person is allowed to freely disrespect anyone younger than him or her. This is just to illustrate the importance of age in the Korean culture.

Koreans often find themselves called by a title in place of their name and this title is usually tied to their age. Or more specifically, their age in comparison to their friend or the rest of group. There are plenty of different titles in the Korean language and might be familiar with a few of them. The term “maknae” refers to the youngest person of a family or group. So if you are the youngest person in your family, you would be the maknae.

In K-Pop, the term “maknae” is very wide spread and is of great importance. It refers to the youngest of the group and plays a huge part in the image of the group. They usually represent innocence and are almost always the cutest and most adorable of the group.”