étalons

Étalon is a French noun with two common senses. In animal husbandry, it designates an adult male horse kept for breeding. An étalon can sire foals and is evaluated for conformation, movement, temperament, and genetic traits. Management considerations include veterinary care, training, and controlling breeding to avoid inbreeding. The female counterpart is the jument, and young horses are called poulain.

In metrology and related fields, étalon means a standard or reference used to calibrate instruments and verify measurements. Étals establish traceability, linking measurements to defined units. They may be physical objects such as mass or length standards, or defined reference values (for example, a conventional temperature or electrical standard). National metrology institutes maintain étalons, and international collaboration coordinates their use. Historically, some étalons were physical artifacts, such as the International Prototype Kilogram, used as the primary mass standard until the redefinition in 2019, when the kilogram became defined by the Planck constant.

Beyond these primary senses, the term étalon is used more broadly as a benchmark or model against which others are compared. The exact sense depends on context, but both uses share the notion of a reference standard or exemplar.