What is a common prefix that indicates "below normal" or "deficient"?

The prefix that indicates "below normal" or "deficient" is "hypo-." This prefix is derived from the Greek language, where it conveys a sense of deficiency or a lower level of something. For example, in medical terminology, "hypoglycemia" refers to a condition of having lower than normal blood sugar levels.

Understanding the meaning of this prefix is crucial in medical contexts, as it helps in the accurate description of patients' conditions, particularly in relation to metabolic processes, hormone levels, and other physiological measurements that may fall below the established norm.

In contrast, "hyper-" signifies an excess or higher than normal level, "sub-" can indicate beneath or under without inherently suggesting deficiency, and "pre-" implies before in time or position, none of which directly relate to a state of deficiency.