| Word Part | 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. |