The prefix "deci-" is derived from the Latin word "decimus," meaning "tenth." It is commonly used in the metric system to denote a factor of one-tenth, or 0.1. For example, a deciliter is one-tenth of a liter, and a decimeter is one-tenth of a meter. This prefix helps standardize measurements in science and everyday life. In addition to its use in the metric system, "deci-" can also appear in various fields such as mathematics and engineering. It provides a clear and concise way to express smaller quantities, making calculations easier and more efficient.