• Any aspect of an individual's life, behavior, an environmental exposure, or an inborn or inherited characteristic that increases the likelihood of a disease, condition or injury.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• Any factor that can cause a person to be more likely to develop a disease. For example, smoking is a risk factor for lung cancer.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• An aspect of personal behavior or lifestyle, environmental exposure, inborn or inherited characteristic, which, based on epidemiological evidence, is known to be associated with a health-related condition considered important to prevent.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021