Erg (noun)

1. A large area of shifting sand dunes, typically found in the Sahara desert and other arid regions.
2. A unit of work or energy, equal to the work done by a force of one dyne acting over a distance of one centimeter.

Origin:

From arabic ارج‎ (arj, "dune, desert").

Examples:

1. The erg was a treacherous landscape, with sand dunes that could shift at any moment.
2. The erg is a unit of energy and work, often used in physics and thermodynamics.
3. Ergonomic design is the practice of designing equipment and devices that are comfortable and efficient to use.
4. Ergonomics is the study of how people interact with their work environment and how to improve that interaction.
5. Ergonomics is the study of how to design equipment and work environments to be comfortable and efficient for the people who use them.