Biofilm: A complex microbial community containing bacteria and fungi. The microorganisms synthesize and secrete a protective matrix that attaches the biofilm firmly to a living or non-living surface. The biofilm contributes to underlying wound infection, chronic inflammation, and delay in healing, and it is present in 80% to 90% of chronic wounds and 6% of acute wounds.

Epibole: Rolled or curled-under closed wound edges. These rolled edges are thickened epidermis that may be callused, dry, scaly, and/or hyperkeratotic. When epibole is present in a wound, it signals to the body that the wound has healed, even though the wound remains open. Epibole must be resolved to allow the wound to close.

Exudate: Fluid drainage originating from tissue in the wound bed in response to injury or inflammation. Exudate types are serous or clear, sanguineous or bloody, purulent, or seropurulent. Exudate quantity is none, scant, small or minimal, moderate, large, or copious.

Infection: The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites with an associated host reaction. Signs of infection include redness, tenderness, warmth, odor, erythema, swelling, fever, pain, and increased white blood cells.

Inflammation: An immune response to foreign bodies or the presence of pathogens. Inflammation results from increased white blood cells. Inflamed tissue is characterized by redness, heat, swelling, and pain.

Necrotic tissue: Tissue that is no longer viable. Can manifest as either slough or eschar. See also Non-viable tissue.

Protease: An enzyme that breaks down proteins. Chronic wounds often have a high level of proteases.

Purulent: Containing or producing pus.

Wound bed preparation: Systematic approach to wound management by identifying and removing barriers to healing, including cleansing and debridement of the wound bed.

Wound edge: The area where intact epithelium meets the wound bed or base. Edge descriptors include indistinct, attached, unattached, rolled or epibole, hyperkeratotic or callused, and fibrotic or indurated.