Here's a breakdown:
* "Dong" (동) means "east".
* "Saeng" (생) means "life" or "birth".
While the literal meaning doesn't directly translate to "younger sibling," it's understood that people born later are "east of" those born earlier.
It's important to note that "dongsaeng" is a very respectful term. It's used to refer to younger siblings in a polite and formal way, even among close friends.