The prefix "deka-" comes from the Greek word "deka," meaning ten. It is used in the metric system to denote a factor of ten. For example, a dekaliter is a unit of volume equal to ten liters, and a dekagram is a unit of mass equal to ten grams. In scientific contexts, "deka-" helps simplify measurements by providing a convenient way to express larger quantities. This prefix is part of the International System of Units (SI), which standardizes measurements across various fields, including science, engineering, and medicine.