PREC

Prec is an informal abbreviation that appears in several fields. Because it is not a single standardized term, its meaning is determined by context. In meteorology and hydrology, prec or precip is commonly used as shorthand for precipitation—the process of water released from clouds as rain, snow, sleet, or hail. Precipitation is typically measured using rain gauges or radar and reported in millimeters or inches; records are used in weather forecasts, climate monitoring, and hydrological planning.

In measurement and data contexts, prec is often used as an abbreviation for precision—the degree to which repeated measurements under unchanged conditions yield the same result. Precision contrasts with accuracy and is a key aspect in instrument calibration, data quality, and the specification of significant figures. In tables or code, a header or variable named prec may indicate the number of digits retained or the precision of a measurement.

In mathematics and computer science, prec is sometimes used as a textual shorthand for "precedes" or a precedence relation, particularly in discussions of orderings or parsing. The standard mathematical symbols vary by notation, with symbols such as ≺ or the LaTeX \prec playing a similar role.

Because prec has multiple meanings, readers should rely on surrounding text to determine which sense is intended.