Which prefix indicates "all"?

The prefix that indicates "all" is "pan-." This prefix is derived from Greek, and it is commonly used in medical terminology to imply a comprehensive or widespread nature. For example, the term "pandemic" refers to a disease that is prevalent over an entire country or the world, indicating that it affects all people in those areas.

In contrast, other prefixes do not convey the same meaning. "Nulli-" means "none" or "not any," often used in terms such as nullipara, referring to a woman who has never given birth. "Poly-" indicates "many" or "several," as seen in terms like polyuria, which refers to excessive urination. "Peri-" signifies "around" or "surrounding," used in terms such as pericardium, which refers to the membrane surrounding the heart. Understanding these prefixes and their meanings helps clarify the scope of conditions or characteristics described in medical terminology.