Addison's disease -- A disease caused by partial or total failure of adrenocortical function, which is characterized by a bronzelike pigmentation of the skin and mucous membranes, anemia, weakness, and low blood pressure.

Aneurysm -- A ballooning of the wall of an artery, a vein, or the heart, at a weak spot in the wall; it is filled with fluid or clotted blood, often forming a pulsating tumor. A sacciform or saccular aneurysm is a localized distension involving only part of the vessel wall; a fusiform aneurysm distends the whole circumference of the artery; in a dissecting aneurysm, the artery wall is split longitudinally by blood pumping through a tear in the inner arterial wall.

Angina pectoris -- a disease marked by brief paroxysmal attack of chest pain precipitated by deficient oxygenation of the heart muscle.

Bacteriology -- the science that deals with bacteria and their relations to medicine, industry, and agriculture. In the 19th; century sometimes used to describe the wider field of microbiology.

Bright's disease -- Any of several kidney diseases, especially those marked by albumin in the urine.

Chorea -- A nervous system disorder marked by spasmodic movements of limbs and facial muscles and by incoordination.

Croup -- A spasmodic laryngitis, especially in infants and young children, characterized by episodes of difficult breathing and hoarse cough.

Diatom -- Any of a class of minute planktonic unicellular or colonial algae with silicified skeletons that form diatomite (diatomaceous earth.)

Histology -- The subset of the study of anatomy that deals with the minute structures, composition, and function of the tissues.

Hodgkin's disease -- A neoplastic (tumorous) disease characterized by progressive enlargement of lymph nodes, spleen, and liver, and by progressive anemia.

Malaria -- A serious, sometimes fatal disease caused by the plasmodium parasite and transmitted to humans through the bites of infected mosquitoes. Once bitten, the parasites travel to the victim's liver, enter the liver cells, grow, multiply, and begin attacking the red blood cells. Symptoms of malaria include a fever and flu-like illness, including shaking, chills, headache, muscle aches, and tiredness. If untreated, some forms of malaria may cause kidney failure, seizures, delirium, coma, and death.

Meningitis -- Inflammation of the three membranes (meninges) that envelop the brain and spinal cord, usually caused by bacterial or viral infection.

Microbe -- any minute living organism, typically single-celled, though the organism may be colonial. This term is applied most frequently to those extremely small forms of life, including bacteria and fungi, which are capable of causing disease in animals.

Nephritis -- An acute or chronic inflammation of the kidney caused by infection, degenerative process, or vascular disease.

Pathology -- That branch of medicine that treats of the essential nature of the disease, especially of the structural and functional changes in tissues and organs of the body that are caused by disease.

Pernicious anemia -- A severe anemia marked by a progressive decrease in the number of red blood cells and by pallor, weakness, and gastrointestinal and nervous disturbances; caused by a deficiency of vitamin B12.

Phthisis -- A progressively wasting or consumptive condition, especially pulmonary tuberculosis.

Physiology -- A branch of biology that deals with the functions and activities of life or of living matter (e.g., organs, tissues, or cells) and of the physical and chemical phenomena involved.

Platelets -- Disc-shaped structures found in the blood of all mammals and chiefly known for their role in blood coagulation.

Pleurisy -- An inflammation of the membranes covering the lungs and lining the thoracic cavity, usually caused by a lung infection.

Pneumonia -- An acute or chronic disease marked by inflammation of the lungs and caused by viruses, bacteria, and/or other microorganisms or physical and chemical irritants.

Polyzoa -- A class of colonial aquatic invertebrate animals, of small size and various forms (also called Bryozoa)

Smallpox -- An acute contagious disease caused by a poxvirus and characterized by fever, a severe skin eruption of pustules, sloughing, and scar formation. Disfiguring and sometimes fatal, it was a common disease until widespread vaccination efforts began in the 20th century. It is now considered to be eradicated.

Tabes dorsalis -- A slowly progressive degeneration of the posterior columns and posterior roots and ganglia of the spinal cord, occurring 15 to 20 years after an initial syphilis infection; characterized by wasting, pain, lack of coordination of voluntary movement and reflexes, and disorders of sensation, nutrition, and vision (also called locomotor ataxia.)

Trichinella spiralis -- A small slender worm that in the larval state is parasitic in the voluntary muscles of flesh-eating mammals (e.g., humans and swine.)

Trichinosis -- Infestation with or disease caused by the trichinella spiralis parasite, marked by muscular pain, shortness of breath, fever, and swelling.

Tuberculosis -- Any of the infectious diseases of humans or other animals caused by species of Mycobacterium and characterized by the formation of tubercles and caseous necrosis in the tissues. In humans, the most common form is pulmonary tuberculosis, which if untreated, can result in tuberculous pneumonia, tuberculous granulation tissue, caseous necrosis, calcification, and cavity formation. Symptoms include weight loss, fatigue, night sweats, and wasting, with purulent or bloody sputum, and chest pain.

Typhoid fever or enteric fever -- An acute, highly infectious disease caused by the bacillus Salmonella typhi transmitted chiefly by contaminated food or water and characterized by high fever, headache, coughing, intestinal hemorrhaging, and rose-colored spots on the skin.