Glossary try the best to avoid the use of medical terms that could make it more difficult to understand the information on this website. Still, there are a number of terms that can't be avoided and that are useful to know because they are so often used by the doctors, nurses, and other medical professionals with whom you might speak. The list below includes the terms used on for which we have provided definitions.

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Term Definition

Into or within a vein


Within a muscle, as an injection


A tumor of the insulin-producing islet cells in the pancreas, causing low blood glucose levels


1) A substance that stops, blocks, or slows down the action of an enzyme
2) A substance that stops or impedes a process from taking place in the body


The response of body tissues to injury such as trauma or infection. Inflammation is a complex process that can be localized or systemic. When localized, it causes pain, heat, swelling and redness of the affected area; when systemic, it may present as a general feeling of malaise with fatigue and fever.


Disease caused by microorganisms


Tissue death caused by the blockage of blood flow by a blood clot or other material

Incubation period

Time between exposure to an infectious agent, such as a virus, and the onset of symptoms of disease


Rate at which new cases of a disease occur within a population

In vivo

Within the body; within a living environment

In vitro

Outside the body; in the clinical lab, in an artificial environment such as a test tube or petri dish

In utero

Within the uterus

in situ

 1. confined to the original site

2. in the original position


Shallow, fluid-filled blisters surrounded by yellow crusts


Pertaining to a substance that decreases the body's normal immune response