Particle size refers to how big or small individual particles are. It describes the dimensions or diameter of the particles, which can range from very tiny to relatively large. Full definition
If you're suspicious of fleas, be on the lookout for black particles the size of ground pepper on your pet's skin near the tail. (petsmagazine.ca)
After seven weeks, both groups had a big reduction in heart disease risk (reduced LDL cholesterol, triglycerides and increases in LDL particle size — good). (healthyeatingharbor.com)
These images are usually offered to support representations of small particle size distributions. (silver-colloids.com)