Mesh:

A measure of fineness of a woven material, screen, or sieve; e.g., a 200-mesh sieve has 200 openings per linear inch.

A 200-mesh screen with a wire diameter of 0.0021 in.

(0.0533 mm) has an opening of 0.074 mm, or will pass a particle of 74 microns.

See micron.