Skip to main content
CSTSetup
Log in
Dictionary

Nursing and medical dictionary

Nursing and medical terms in plain words: what each one means, how to say it, the word parts it is built from, and why it matters at the bedside.

Word of the day · Oct 18, 2026

Mallory-Weiss tear

MAL-er-ee WYS tair · noun

A tear in the lining where the esophagus meets the stomach.

Full entry
left ventricleThe heart's lower left chamber, which pumps oxygen-rich blood into the aorta and out to the body.
left-sided heart failureHeart failure in which the left ventricle cannot pump enough blood out to the body.
lei/oA word root that means smooth.
Leopold maneuversFour steps of feeling the pregnant abdomen with the hands to find how the fetus is lying in the uterus.
lesionAn area of tissue that has been damaged or has changed from normal, such as a sore, wound, lump or spot.
letdownThe reflex that pushes milk out of the breast's milk glands toward the nipple during breastfeeding.
lethargyA state of being very drowsy, slow and hard to keep awake, or having little energy.
leuk/oA word part that means white.
leukemiaA cancer of the blood-forming cells in the bone marrow, in which abnormal white blood cells are made in large numbers.
level of consciousnessHow awake, alert and aware of their surroundings a person is.
levetiracetamAn anticonvulsant drug, given by mouth or IV, used to prevent and treat seizures.
Levine signA clenched fist held against the chest by a person describing chest pain.
levodopaThe main drug for Parkinson disease, which the brain turns into dopamine.
levofloxacinA fluoroquinolone antibiotic, given by mouth or IV, used for lung, urinary and other bacterial infections.
levonorgestrelA progestin hormone used in birth control pills, hormonal IUDs and the morning-after pill.
levothyroxineA man-made form of the thyroid hormone thyroxine (T4), taken to replace hormone the thyroid does not make.
LGBTQIA+A short form for sexual and gender minority groups: L lesbian, G gay, B bisexual, T transgender, Q queer or questioning, I intersex, A asexual, + others.
Lhermitte signAn electric-shock feeling that runs down the back, and sometimes into the arms or legs, when the neck is bent forward.
libidoSexual desire: a person's interest in or drive toward sexual activity.
licensed practical nurseA nurse who has passed the NCLEX-PN and is licensed to give basic nursing care under an RN or other provider.
licensureThe granting of a license by a government body that gives a person legal permission to practice a profession.
lidocaineA local anesthetic that numbs an area, also given by IV to treat some fast, abnormal heart rhythms.
life spanThe whole length of a person's life, from conception or birth to death.
lifestyleThe way a person lives day to day, including eating, activity, sleep, smoking, alcohol use and stress.
ligamentA tough band of tissue that connects one bone to another at a joint.
lightheadednessA feeling of being faint or woozy, as if about to pass out.
limbAn arm or a leg.
limited English proficiencyLimited ability to read, speak, write or understand English, for a person whose main language is another one.
lindaneA shampoo or lotion that kills lice and scabies mites, used only when safer treatments have failed or cannot be used.
lipaseAn enzyme, made mainly by the pancreas, that breaks down fats; its blood level is a common lab test.
lipidA fat or fat-like substance in the body or food, such as cholesterol and triglycerides.
lipid panelA blood test that measures fats in the blood: total cholesterol, LDL and HDL cholesterol, and triglycerides.
lipoproteinA particle made of fat and protein that carries cholesterol and other fats through the blood.
lisinoprilAn ACE inhibitor drug that lowers blood pressure and protects the heart and kidneys.
literA metric unit of volume equal to 1,000 milliliters, a little more than a US quart.
lith/oA word root that means stone.
lithiumA mood-stabilizing drug used mainly to treat and prevent the mood episodes of bipolar disorder.
lithium levelA blood test that measures how much of the mood-stabilizing drug lithium is in the blood.
lithotomyA position lying on the back with the hips and knees bent and the legs raised and spread apart, often in stirrups.
liverA large organ in the right upper abdomen that processes nutrients, makes bile and clotting factors, and clears drugs and toxins from the blood.
liver diseaseAny condition that damages the liver or keeps it from working normally.
liver function testsA group of blood tests that check how well the liver is working and whether its cells are damaged.
living willA written legal document that says which medical treatments a person does or does not want if they cannot speak for themselves.
lob/oA word part that means lobe, a rounded section of an organ.
lobeA rounded section or division of an organ, such as the brain, lung, liver or ear.
LOCAn abbreviation for level of consciousness, or for loss of consciousness.
local anesthesiaNumbing medicine applied to or injected into one small area, so a procedure there is not felt while the person stays awake.
local anestheticA drug that blocks feeling in one part of the body without making the person unconscious.
localizedLimited to one area of the body, rather than spread through it.
lochiaThe vaginal discharge of blood, mucus and tissue from the uterus after childbirth.