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sheet graft

SEE: under graft.

shelf life

1. The length of time a food may be kept in storage and still be considered safe to eat. 2. The length of time a substance, preparation, or medication can be kept without separation or chemical changes of its components. 3. The length of time that a drug or biomaterial will maintain its effectiveness or integrity.

shelf-life extension

Preservation of the purity and potency of a therapeutic agent beyond its expected expiration date.


(shel) A hard covering, as that for an egg or turtle.


(shĕ-lăk′) A refined resinous substance obtained from plants that contain the secretions of certain insects. It is used in paints, varnishes, dry compounding, and in dentistry.

image Some people may develop contact dermatitis after exposure to shellac.


(shel′fish″) Any of a group of marine animals that include mollusks and crustaceans. Allergic reactions (urticaria, asthma, angioedema, anaphylaxis) to a wide variety of shellfish are among the most common causes of food allergy in humans.

shell shock SEE: under shock.

shelter-in-place, sheltering-in-place

(shel′tĕr) Finding protection from an environmental hazard by sealing oneself in a safe and secure location instead of fleeing or evacuating. One must stay indoors and rely on stored supplies or, if materials must be imported from a contaminated environment, rely on filtration systems that remove toxins, viruses, bacteria, and other potentially dangerous materials until the hazard passes.

Shenton line

(shent′ŏnz) [Thomas Shenton, Brit. radiologist, 1872–1955] In radiography, a line determining the relationship of the head of the femur to the acetabulum. The line follows the inferior border of the ramus of the pubic bone and, continuing outward, follows the curve down the medial border of the neck of the femur.

Sherrington phenomenon

(shĕr′ĭng-tŏn) [Sir Charles Scott Sherrington, Brit. physiologist, 1857–1952] Contraction of denervated skeletal muscle by stimulating autonomic cholinergic fibers innervating its blood vessels.


(shē-at′soo) [Japanese shiatsu(ryōhō), fm shi, finger, + atsu, pressure + ryōhō, treatment] A traditional Japanese form of alternative medicine consisting of the therapeutic application of palm and finger pressure to acupuncture points.


(shēld) 1. A cover or barrier; any layer or structure that limits exposure to a potentially toxic agent, such as a source of body fluids or radiation. 2. In biology, a protective plate or hard outer covering. GER: shielding.

face s. A mask, typically made of clear plastic, that protects the mucous membranes of the eyes, ...

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