What is the prefix that means small?

The prefix that means small is "micro-." This prefix originates from the Greek word "mikros," which translates to "small" or "little." It is commonly used in various scientific and medical terminology to indicate something that is tiny or on a small scale. For instance, in terms such as "microorganisms," it denotes organisms that are too small to be seen with the naked eye.

While "mini-" also suggests something that is small, it is more informal and often refers to scaled-down versions of objects rather than a term used in scientific contexts. "Pico-" signifies one trillionth of a unit in the metric system, which implies an even smaller scale than micro- but is not typically used as a standalone term for small. The prefix "sub-" generally indicates something that is beneath or below and does not convey the idea of small size effectively. Therefore, "micro-" is the most accurate prefix for indicating smallness in this context.