What does sub mean in Greek and Latin words?

In both Greek and Latin, "sub" generally means "under," "below," or "beneath." In Latin, it is commonly used as a prefix in Words like "submarine" (underwater) and "subterranean" (underground). Similarly, in Greek-derived terms, it conveys a sense of being below or inferior in position or status. This prefix is often used to indicate a lower level or secondary status in various contexts.