particle size; particle diameter
Technical term used in physics, chemistry, and materials science. Often interchangeable with 粒径 (りゅうけい).
See also: 粒径
この粉体の平均粒子径は約50マイクロメートルです。
The average particle size of this powder is about 50 micrometers.
Compound of 粒子 (りゅうし, 'particle') and 径 (けい, 'diameter').