Dictionary of Medical Terms

Gain a better understanding of medical terminology by searching our dictionary of more than 1,300 terms.

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All terms that start with the letter R

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rabies

A fatal, if untreated, viral disease of mammals that’s spread to humans by the bite of infected animal.
rad

Radiation absorbed dose. A unit of measurement of the absorbed dose of ionizing radiation.
radiculopathy

A disease or other problem affecting a nerve root.
radioisotope

A radioactive form of an element. Used in certain diagnostic tests.
radiology

The branch of medicine that deals with the use of x-rays.
radon

A colorless, radioactive gas produced by the decay of radium. The presence of sufficient quantities of this gas in homes…
rash

Visual marks or spots that appear on the skin.
Raynaud's phenomenon

A circulation disorder characterized by changes of blood flow, resulting in the hands and feet becoming pale, followed by redness…
recrudescence

To reoccur after a temporary absence.
rectum

The last portion of the large intestine.
reflux

A return flow.
refraction

1. The bending of a ray or wave of light from one medium to a medium of a different density…
regurgitation

The return of partly digested food from the stomach to the mouth or of blood in a reverse direction through…
rehabilitation

The process of restoring one’s ability to live as normally as possible after an injury or illness.
Reiter's syndrome

A complex group of symptoms marked by inflammation of the urethra or cervix, conjunctiva and joints.
relapse

The return of a disease after its apparent resolution.
REM

Rapid eye movement. The phase of sleep associated with dreaming and distinguished from the other stages of sleep by rapid…
remedy

Anything that cures.
remission

Improvement of the symptoms of a disease.
renal

Having to do with the kidney.
reservoir

A medical term used to describe a source of organisms causing a disease.