Which prefix signifies "under; below; beneath"?

The prefix that signifies "under; below; beneath" is indeed sub. This prefix is derived from Latin, where it carries the meaning of being beneath or under something. For example, in the term "submarine," "sub" indicates that it operates beneath the surface of the water.

The other prefixes have different meanings that do not align with "under; below; beneath." The prefix post means "after" or "behind," while non signifies "not" or the absence of something. Inter, on the other hand, refers to "between" or "among." Understanding these prefixes is important for grasping the meanings of various terms in context, especially in medical or scientific vocabulary where precision of language is paramount.