Autoimmune disease: Occurs when a specific adaptive immune response is mounted against the self. It is not known what triggers the autoimmune response, but susceptibility to most autoimmune diseases shows a significant genetic component. Environmental factors such as infection or diet are likely to play a role in pathogenesis.

Chronic rheumatism:Non-specific affection of the joints, slow in progress, producing a painful thickening and contraction of the fibrous structures, interfering with motion and causing deformity.

Connective tissue: Structures that bind and support the body, such as tendons, joints, ligaments, bones, cartilage, and synovium or joint lining. The blood and lymph may be regarded as connective tissue as well.

Connective tissue disease(s): (Also collagen disease) Any of a group of diseases, as systemic lupus erythmetosus, polyarteritis, scleroderma, and rheumatoid arthritis, involving inflammation or degeneration of connective tissue and accompanied by deposition of fibrinous material.

Fibromyalgia:Muscular rheumatism; in the absence of objective abnormalities, a term used to denote aching, soreness or stiffness; commonly associated problems are fatigue, sleep disturbance, headaches.

Neuropathy:A classical term for any disorder affecting any segment of the nervous system. In contemporary usage, a disease involving the cranial or spinal nerves.

Rheumatism: An indefinite term applied to various conditions with pain or other symptoms which are of articular origin or related to other elements of the musculoskeletal system. (articular= relating to a joint).

Rheumatoid arthritis: A common inflammatory joint disease that is probably due to an autoimmune response. The disease is accompanied by the production of rheumatoid factor, an IgM anti-IgG antibody that may also be produced in normal immune responses.

Scleroderma:Dermatosclerosis; hide-bound or skinbound disease; thickening of the skin caused by swelling and thickening of fibrous tissue, with eventual atrophy of the epidermis (skin layer); a manifestation of progressive systemic sclerosis.

Systemic:Relating to a system; of or pertaining to the body; relating to the entire organism as distinguished from any of its individual parts.

Systemic Lupus Erythematosus (SLE): An inflammatory connective tissue disease with variable features, frequently including fever, weakness and fatigability, joint pains or arthritis resembling rheumatoid arthritis, diffuse erythematous skin lesions on the face, neck, or upper extremities, with liquefaction degeneration of the basal layer and epidermal atrophy, lymphadenopathy (enlarged lymph nodes), pleurisy (inflammation of membrane around lungs) or pericarditis (inflammation of membrane around the heart), glomerular lesions (of the capillaries) , anemia, hyperglobulenemia, a positive L.E. cell test, and other evidence of autoimmune phenomenon.

Sources:
Stedman's Medical Dictionary, 24th ed., published by Williams and Wilkins, Baltimore.
ImmunoBiology: The Immune System in Health and Disease by Janeway & Travers, published by Current Biology Limited/Garland Publishing Inc. , New York/London.
Random House Unabridged Dictionary, 2nd Edition