significant figure

This term is a technical expression used primarily in science, engineering, and mathematics to communicate the precision of a measurement. It distinguishes between digits that are known with certainty and those that are estimated, ensuring that a calculated result does not claim more accuracy than the original measurements allow.

In a practical laboratory or classroom setting, the term is used as a rule for rounding. For example, if a measurement is recorded to three significant figures, it implies the instrument used had a specific limit of resolution. Misusing this term in a non-technical context would be unusual, as it refers specifically to numerical precision rather than the "importance" of a person or event.