Wearing away or removal of the paint film when scrubbed with a brush, sponge or cloth.
Areas that need frequent cleaning require a highly washable premium quality paint formulated to provide such performance. High traffic areas may require a low sheen, semi gloss or gloss paint rather than a flat paint to provide good scrub resistance. Allow adequate dry time, as scrub resistance will not fully develop until the paint is fully cured. Typically, this will be one week. Try washing the painted surface with the least abrasive material and mildest detergent first.
Source: The Paint Quality Institute