Antibody: An immunoglobulin, a specialized immune protein, produced because of the introduction of an antigen into the body, and which possesses the remarkable ability to combine with the very antigen that triggered its production.
Bell’s palsy: Paralysis of the facial nerve, the nerve that supplies the facial muscles on one side of the face. Bell’s palsy is also called facial nerve paralysis.
Borrelia: A group of bacteria that are helical spirochetes of the genus Borrelia. Some species of Borrelia cause relapsing fever in humans and animals. Named after Amedee Borrel (1867-1936), French bacteriologist.
Borrelia burgdorferi: The spirochete (a type of bacteria) that causes Lyme disease. Named after its discoverer, Dr. Willy Burgdorfer.
Chronic: This important term in medicine comes from the Greek chronos, time and means lasting a long time.
Erythema: A redness of the skin resulting from inflammation, for example, as caused by sunburn.
Erythema chronicum migrans (EM): The classic initial rash of Lyme disease. In the early phase of the illness, within days to weeks of the tick bite, the local skin develops an expanding ring of unraised redness. There may be an outer ring of brighter redness and a central area of clearing.
Lyme disease: Lyme disease is a bacterial illness caused by a bacterium called a “spirochete.” Lyme disease is spread by ticks when they bite the skin. Lyme disease can cause abnormalities in the skin, joints, heart and nervous system.
Peripheral neuropathy: A problem with the functioning of the nerves outside the spinal cord. Symptoms may include numbness, weakness, burning pain (especially at night), and loss of reflexes.
Spirochete: A microscopic bacterial organism in the Spirochaeta family. Spirochetes have a worm-like, spiral-shaped form, and wiggle vigorously when viewed under a microscope. Treponema pallidum, the cause of syphilis, is a particularly well-known member spirochete.
For another good glossary see here.