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Medical Dictionary: n

Word	Definition
N&V	nausea and vomiting
Na	sodium
NAD	no acute distress
nails	The thin, translucent, horny plates that cover the dorsal surfaces of the distal phalanges of the fingers and toes
nano-	one-billionth, dwarfism
nanospheres	Spherical particles of nanometer dimensions.
narc/o	sleep, numbness, stupor
narcissism	Excessive admiration of self.
narcolepsy	A chronic brain disorder that involves poor control of sleep-wake cycles.
narcotics	Agents that dull the sense of pain and cause somnolence. They are comprised of natural or synthetic derivatives of opium or morphine or any substance that has such effects.
nares	An external opening in the nasal cavity. A nostril.
nas/o	nose
nasal cavity	The proximal portion of the respiratory passages on either side of the nasal septum. On inhalation the air is warmed, moistened, smelled and filtered.
nasal decongestants	Drugs designed to treat inflammation of the nasal passages.
nasal lavage	Irrigation of the nose with saline or irrigation solutions to remove irritants, allergens or microorganisms from the nose.
nasal septum	The partition separating the two nasal cavities in the midplane.
nasion	A point on the skull where the top of the nose meets the ridge of the forehead.
nasolacrimal duct	A tubular duct that conveys tears from the lacrimal gland to the nose.
nasopharynx	The top portion of the pharynx situated posterior to the nose and superior to the soft palate.
nat/o	birth
natal	Relating to birth.
natr/o	sodium
nausea	An unpleasant sensation in the stomach accompanied by the inclination to vomit.
NCI	National Cancer Institute
NDC	National Drug Code
nebulizers	Devices that create an aerosol a mist (vapor). It is used to administer drugs or to humidify air.
neck	The body part connecting the head to the rest of the body.
necr-	death, corpse
necrobiosis	The natural death of cells due to age, use or development.
necrobiotic disorders	A group of disorders characterized by swelling, basophilia, and distortion of collagen bundles in the dermis.
necrosis	Pathological cell or tissue death, caused by damage, trauma, ischemia or infection.
necrotizing fasciitis	A rare but serious infection caused by bacteria. It destroys skin, fat and tissue covering muscles.
needle sharing	Usage of a single needle among two or more people for injecting drugs, a high-risk behavior for contracting infectious disease.
negativism	Behavior marked by extreme skepticism and persistent resistance to external advice.
nemosis	The process of cell activation and death in fibroblasts.
neo-	new
neocortex	The largest portion of the cerebral cortex, the outer surface of the cerebrum, responsible for spatial reasoning, thought, language, memory and sensory perception.
neonatal	Pertaining to a new baby, for the first 28 days after birth.
neonate	An infant less than one month old.
neoplasia	The formation of a neoplasm
neoplasm	An abnormal new growth of tissue. Also called a tumor.
neovascularization	Formation of new blood vessels.
nephr/o	kidney
nephralgia	Pain in the kidney.
nephrectomy	Excision of kidney.
nephritis	Inflammation of any part of the kidney.
nephrolithiasis	Formation of kidney stones.
nephrology	A subspecialty of medicine concerned with the kidney.
nephron	Very small filtering structures in the kidneys.
nephrosclerosis	Hardening of the kidney due to infiltration by fibrous connective tissue. Usually caused by chronic hypertension.
nephrosis	Any degenerative disease of the kidney.
nephrotic syndrome	Disease of the kidney without inflammatory or neoplastic components.
nerve	A cordlike structure of the body, comprising a collection of conducting fibers that convey impulses between a part of the central nervous system and another body region.
nerve block	Interruption of neural conduction in peripheral nerves or nerve trunks by the injection of a local anesthetic agent.
neur/o	nerve
neural conduction	The propagation of the nerve impulse along the nerve away from the site of an excitation stimulus.
neuralgia	Intense pain that occurs along the course of a peripheral or cranial nerve.
neurapraxia	A peripheral nerve injury marked by a temporary loss of conduction of impulses.
neurasthenia	A mental disorder characterized by chronic fatigue and concomitant physiologic symptoms.
neuri-	nerve, nervous system
neuritis	A general term indicating inflammation of a nerve, often marked by pain, numbness or tingling, or paralysis.
neurocytoma	A brain tumor of undifferentiated cells of nervous origin.
neurodermatitis	An extremely variable eczematous skin disease that is presumed to be a response to prolonged vigorous scratching, rubbing, or pinching to relieve intense pruritus.
neuroendocrine	Pertaining to the relationships between the nervous and endocrine systems
neuroendocrinology	The study of the relationships between the nervous system and the endocrine system.
neurofibroma	A moderately firm, benign, encapsulated tumor resulting from proliferation of Schwann cells and fibroblasts that includes portions of nerve fibers.
neurofibrosarcoma	A malignant tumor that arises from small cutaneous nerves, is locally aggressive, and has a potential for metastasis.
neurogenesis	Formation of neurons which involves the differentiation and division of stem cells in which one or both of the daughter cells become neurons.
neuroglia	The supportive tissue of the nervous system
neurological	Pertaining to the nervous system
neurology	A medical specialty concerned with the study of the structures, functions, and diseases of the nervous system.
neuroma	A benign neoplasm composed of nerve cells and nerve fibers.
neuromuscular	Disorders that affect the nerves that control voluntary muscles.
neuron	The basic cellular unit of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system.
neuroretinitis	Inflammation of the optic nerve and retina.
neurotransmitters	Chemical messengers that carry signals to other cells in the body.
neurotropic	Having an affinity for the nervous system or the growth of neural tissue.
neutr/o	neutral
neutropenia	Abnormally decrease in the numbers of neutrophils in circulating blood.
neutrophils	A type of white blood cell that is an early responder to infections.
nev/o	mole, birthmark
nevus	A malformation of skin that is present at birth, including moles and birthmarks.
NG	nasogastric
NGF	nerve growth factor
niacin	A water-soluble vitamin B complex.
nicotine	A highly toxic alkaloid.
nictation	A reflex that closes and opens the eyes rapidly. Blinking.
NICU	neonatal intensive care unit
NIDDM	noninsulin-dependent diabetes mellitus
night blindness	Failure or reduced ability to see in dim light.
night terrors	A sleep disorder characterized by episodes of abrupt awakening suggesting extreme fright. This condition primarily affects children and young adults.
NIH	National Institutes of Health
nipple	The conic projection on the breast which provides an outlet for milk from the mammary glands.
nitrogen	An element with the atomic symbol N, atomic number 7, comprising 78% of the earth's atmosphere by volume.
nitroglycerin	A vasodilator which relieves angina pectoris.
NK	natural killer
NKA	no known allergies
NMJ	neuromuscular junction
nocebo effect	A negative placebo effect.
noct/i	night
nocturia	Patient needs to wake at night to pass urine.
nocturnal enuresis	Involuntary discharge of urine during sleep at night after expected age of completed development of urinary control.
nocturnal myoclonus	A sleep disorder where the patient moves involuntarily during sleep. Also called periodic limb movement disorder.
nod/o	knot
-noia	mind, will
nomen-	name, pertaining to names
non-	not
norepinephrine	A neurotransmitter that is secreted in response to stress, increasing blood pressure and glucose.
norm-	normal
normotensive	Having normal blood pressure.
norovirus	A virus associated with epidemic gastroenteritis.
nos-	disease
nose	A part of the upper respiratory tract. It includes the external nose, the nasal cavity, and the paranasal sinuses.
nosocomial pneumonia	Pneumonia acquired during a hospital stay.
nostrums	Medicines whose effectiveness is unproven and whose ingredients are often secret. A quack remedy.
noto-	back
noxae	Anything harmful to the body.
NP	nurse practitioner
NPN	nonprotein nitrogen
NPO	nothing by mouth
NS	normal saline
NSAID	nonsteroidal anti-inflammatory drug
NSR	normal sinus rhythm
NTD	neural tube defect
nucle/o	nucleus
nucleic acid	Any of a group of long, linear macromolecules, either DNA or various types of RNA, that carry genetic information.
nucleotides	The base units of nucleic acids.
nucleus	The part of a cell that contains DNA and RNA.
nulli-	none
nulligravida	A woman who has never been pregnant.
nullipara	A woman who has never borne a child.
nutation	The act of nodding one's head, especially involuntarily.
nutri/o	to nourish
nyct/o	night, darkness
nyctalopia	Night blindness.
nystagmus	A vision condition in which the eyes make repetitive, uncontrolled movements, usually side to side.