• (ingrown nail) Excessive growth of a nail laterally into the nail fold.
  Human Phenotype Ontology (HPO)
  The Human Phenotype Ontology Project, 2025
• Excessive lateral nail growth into the nail fold. Because the lateral margin of the nail acts as a foreign body, inflammation and granulation may result. It is caused by improperly fitting shoes and by improper trimming of the nail.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• (ingrown toenail) A condition in which the nail grows into the nailbed secondary to downward pressure, generally caused by ill-fitting shoes. Symptoms include pain, erythema, and edema, and may result in infection if it remains untreated.
  NCI
  U.S. National Cancer Institute, 2021
• (ingrown toenail) A condition in which the side of a toenail pierces the skin, causing pain, swelling, and sometimes infection.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• An ingrown toenail is incurvation or impingement of a nail border into its adjacent nail fold, causing pain. Causes of ingrown toenail include tight shoes, abnormal gait (eg, toe-walking), bulbous toe shape, excessive trimming of the nail plate, or congenital variations in nail contour (eg, congenital pincer nail deformity). Sometimes an...
  Merck Manuals
  Merck & Co., Inc., 2025
• Ingrown toenail (onychocryptosis) is a fairly frequent problem resulting from either growth of nail fold inwards into the nail bed or abnormal embedding of the nail plate into the nail groove, causing significant discomfort. Although often thought to be synonymous, the terms ingrown nail and paronychia refer to different conditions.
  Medscape
  WebMD, 2025
• Ingrown toenails are a common condition in which the corner or side of a toenail grows into the soft flesh. The result is pain, redness, swelling and, sometimes, an infection. Ingrown toenails usually affect your big toe.
  Mayo Clinic
  Mayo Foundation for Medical Education and Research, 2025