abscess: abscess n. a localised collection of pus anywhere in the body, surrounded and walled off by damaged and inflamed tissues. A *boil is an example of an abscess within the skin. The usual cause is local bacterial infection, often by staphylococci, that the body's defenses have failed to overcome. In a cold abscess, sometimes due to tubercle organisms, there is swelling, but little pain or inflammation (as in acute abscesses). Antibiotics, aided by surgical incision to release pus where necessary, are the usual forms of treatment.