wall stress: Force on the wall of the heart muscle caused by pressure inside the heart's pumping chamber; excessive wall stress can impair the heart's ability to pump and increase the heart's need for oxygen.

warfarin: An anticoagulant drug that prevents blood clotting; people taking it must have regular blood tests to determine that their blood does not clot too readily or too slowly.

wart: An abnormal fibrous growth caused by a viral infection.

water brash: Salty-tasting salivary secretions stimulated by gastroesophageal reflux.

Weber test: A hearing test that uses a tuning fork to diagnose one-sided hearing loss.

Wernicke-Korsakoff syndrome: An irreversible state of acute confusion and amnesia that develops in alcoholics as a result of malnutrition-related thiamine deficiency.

Wernicke's area: The brain region responsible for the comprehension of speech.

whiplash: The popular term for muscle and ligament damage resulting from rapid and extreme extension and flexion of the neck. The term is also used for the accident causing the injury, most often a rear-end motor vehicle accident.

white matter: The inner portion of the brain, composed primarily of axons, each surrounded by a myelin sheath that insulates the nerve fibers (and appears white). Messages are sent between different regions of the brain (gray matter) via these nerve fibers.

white-coat hypertension: Blood pressure that is elevated in a doctor's office but is normal at home.

will: A legal document that describes what should be done with a person's assets after his or her death.

withdrawal: A response to danger or stress characterized by apathy, lethargy, and depression; or the physical or psychological response to a sudden lack of an addictive substance such as alcohol or nicotine.

working memory: A type of short-term memory process that involves temporarily storing and manipulating information.