(Many of the medical names used in historical records are vastly different from the terms used in medicine today.  This causes many problems for those of us who are researching our family histories.  In order to help my fellow researchers, I have compiled this list of archaic medical terms and their definitions.  It is far from complete, but covers the names of the most commonly found medical conditions. - Marjorie Norris)

Ablepsy - Blindness

Acute mania- severe insanity

Affrighted- Literally frightened to death; used to describe a stress induced heart attack or stroke
Ague - Malarial Fever; also used to describe any intermittent fever characterized by periods of chills, fever and sweating
American plague - Yellow fever
Anasarca - Generalized massive edema
Aphonia - Laryngitis
Aphtha - The infant disease "thrush"
Apoplex/Apoplexy A stroke; Paralysis due to stroke
Asphicsia/Asphycsia - Cyanosis and lack of oxygen

Asthenia- debilitation
Atrophy - Wasting away or diminishing in size
Bad Blood - Syphilis
Bilious fever - Typhoid, malaria, hepatitis or elevated temperature and bile emesis
Biliousness - Jaundice associated with liver disease
Black plague or black death - Bubonic plague
Black fever - Acute infection with high temperature, dark red skin lesions and high mortality rate
Black pox - Black Small pox
Black vomit - Vomiting old black blood due to ulcers or yellow fever
Blackwater fever - Dark urine associated with high temperature
Bladder in throat - Diphtheria
Blood poisoning - Bacterial infection; septicemia
Bloody flux - Bloody stools; usually in relation to dysentery
Bloody sweat - Sweating sickness
Bone shave Sciatica; pain in low back and hips
Brain fever Meningitis or typhus; any inflammation of the brain or nervous system 
Breakbone - Dengue fever
Bright's disease - Chronic inflammatory disease of kidneys; pyleonephritis
Bronze John - Yellow fever
Bule - Boil, tumor or swelling
Cachexy - Malnutrition
Cacogastric - Upset stomach
Cacospysy - Irregular pulse
Caduceus - Subject to falling sickness or epilepsy
Camp fever - Typhus; aka Camp diarrhea
Canine madness - Rabies, hydrophobia
Canker - Ulceration of mouth or lips; also used for herpes simplex
Catalepsy - Seizures, trances
Catarrhal - Nose and throat discharge from cold or allergy
Cerebritis - Inflammation of cerebrum or lead poisoning

Choak- Croup
Chilblain - Swelling of extremities caused by exposure to cold
Child bed fever - Infection of uterus following birth of a child
Chin cough - Whooping cough
Chlorosis - Iron deficiency anemia
Cholera - Acute severe contagious diarrhea with intestinal lining sloughing
Cholera morbus - Characterized by nausea, vomiting, abdominal cramps, elevated temperature
Cholecystitus - Inflammation of the gall bladder
Cholelithiasis - Gall stones
Chorea - Disease characterized by convulsions, contortions and dancing
Cold plague - Ague which is characterized by chills
Colic - An abdominal pain and cramping
Congestive chills - Malaria
Consumption - Tuberculosis
Congestion - Any excessive collection of blood or other fluid in an organ, body part, or blood vessel

Congestive chills - Malaria with diarrhea
Congestive fever - Malaria
Corruption - Infection
Coryza - A cold
Costiveness Constipation

Cowpox- Nonfatal disease similar to smallpox, affecting cattle and transmittable to humans
Cramp colic - Appendicitis
Crop sickness - Overextended stomach
Croup - Laryngitis, diphtheria, or strep throat; any obstructive condition of the larynx or trachea, characterized by hoarse, raspy cough.  Chiefly seen in infants and children
Cyanosis - Dark skin color, generally bluish gray, caused by a lack of oxygen in blood
Cynanche - Diseases of throat
Cystitis - Inflammation of the bladder
Day fever - Fever lasting one day; sweating sickness
Debility - Lack of movement or staying in bed
Decrepitude - Feebleness due to old age
Delirium tremens Hallucinations, tremors, mental confusion due to chronic alcoholism
Dengue - Infectious fever endemic to East Africa
Dentition - Cutting of teeth
Deplumation - Tumor of the eyelids which causes hair loss
Diary fever - A fever that lasts one day
Diphtheria - Contagious disease of the throat
Distemper - Usually animal disease with malaise, discharge from nose and throat, anorexia
Dock fever - Yellow fever

Domestic Illness- mental breakdown, depression
Dropsy - Edema (swelling) of the body or any body part due to build up of clear watery fluid; often caused by kidney or heart disease; common term for congestive heart failure
Dropsy of the Brain - Encephalitis
Dry Bellyache - Lead poisoning
Dyscrasy - An abnormal body condition
Dysentery - Inflammation of colon with frequent passage of mucous and blood; may refer to a number of disorders which produce these symptoms
Dysorexy - Reduced appetite
Dyspepsia - Indigestion and heartburn. Heart attack symptoms
Dysury - Difficulty in urination
Eclampsia/ Eclampsy - Symptoms of epilepsy or convulsions during pregnancy or labor
Ecstasy - A form of catalepsy characterized by loss of reason
Edema- swelling of tissues
Edema of lungs - Congestive heart failure, a form of dropsy
Eel thing - Erysipelas
Elephantiasis - A form of leprosy where extremities are greatly enlarged due to lymphatic blockage
Encephalitis - Swelling of brain; commonly called sleeping sickness
Enteric fever - Typhoid fever
Enterocolitis - Inflammation of the intestines
Enteritis - Inflations of the bowels

Epilepsy- Convulsive or seizure disorder; disorder of the nervous system
Epitaxis - Nose bleed
Erysipelas - Contagious skin disease, due to Streptococci with vesicular and bulbous lesions
Extravasted blood - Rupture of a blood vessel
Falling sickness - Epilepsy

Fainting Fits- epilepsy
Fatty Liver - Cirrhosis of liver
Fits - Sudden attack or seizure of muscle activity
Flux - An excessive flow or discharge of fluid like hemorrhage or diarrhea; used to describe dysentery
Flux of humour - Circulation
French pox - Syphilis

Frogg- croup

Furuncle- boil or skin abcess

Galloping consumption- pulmonary tuberculosis

Gangrene- tissue death due to injury, disease, or reduced blood supply to an area of the body
Gathering - A collection of pus

General paralysis of the Insane- advanced case of syphilis that affects the brain, leading to mental aberrations
Glandular fever - Mononucleosis

Gout- Painful inflammation and swelling of joints caused by build up of uric acid in the bloodstream
Great pox - Syphilis
Green fever / Sickness - Anemia
Grippe/Grip - Influenza like symptoms
Grocer's itch - Skin disease caused by mites in sugar or flour
Heart sickness - Condition caused by loss of salt from body
Heat stroke - Body temperature elevation because of surrounding environmental temperature; Coma and death result if not reversed
Hectical complaint - Recurrent fever
Hematemesis - Vomiting blood
Hematuria - Bloody urine
Hemiplegy - Paralysis of one side of body
Hip gout - Osteomylitis
Horrors - Delirium tremens
Hydrocephalus - Enlarged head, water on the brain
Hydropericardium - Heart dropsy
Hydrophobia - Rabies
Hydrothroax - Dropsy in chest
Hypertrophic - Enlargement of organ, like the heart
Impetigo - Contagious skin disease characterized by pustules

Impostume-  Abcess
Inanition - Physical condition resulting from lack of food
Infantile paralysis - Poliomylelitis
Intestinal colic - Abdominal pain due to improper diet
Jail fever - Typhus
Jaundice - Condition caused by blockage of intestines
King's evil - Tuberculosis of neck and lymph glands
Kruchhusten - Whooping cough
Lagrippe - Influenza

Leprosy- chronic bacterial disease affecting generally skin and nerves; if untreated, may cause permanent damage to affected areas
Lockjaw - Tetanus or infectious disease affecting the muscles of the neck and jaw. Untreated, it is fatal in 8 days
Long sickness - Tuberculosis
Lues disease - Syphilis
Lues venera - Venereal disease
Lumbago - Back pain
Lung fever - Pneumonia
Lung sickness - Tuberculosis
Lying in - Time of delivery of infant
Malignant sore throat - Diphtheria
Mania - Insanity
Marasmus - Progressive wasting away of body, as in malnutrition

Melancholia- severe depression
Membranous Croup - Diphtheria
Meningitis - Inflations of brain or spinal cord
Metritis - Inflammation of uterus or purulent vaginal discharge
Miasma - Poisonous vapors thought to infect the air
Milk fever - Disease from drinking contaminated milk, like undulant fever or brucellosis; also used to describe fever that develops in relation to lactation
Milk leg - Post partum thrombophlebitis; blood clots and swelling of the legs
Milk sickness - Disease from milk of cattle which had eaten poisonous weeds

Morbilli- measles

Morbus cordis- heart disease; catch all phrase to describe death by natural causes when no exact cause was evident
Mormal - Gangrene
Morphew - Scurvy blisters on the body
Mortification Gangrene; development of necrotic tissue
Myelitis - Inflammation of the spine
Myocarditis - Inflammation of heart muscles
Necrosis - Mortification (death) of bones or tissue
Nephrosis - Kidney degeneration
Nepritis - Inflammation of kidneys
Nervous prostration - Extreme exhaustion from inability to control physical and mental activities
Neuralgia - Described as discomfort, such as "Headache" was neuralgia in head
Nostalgia - Homesickness

Oedema- swelling, fluid retention; dropsy
Palsy - Paralysis or uncontrolled movement of controlled muscles.

Paroxysm - Convulsion
Pemphigus - Skin disease of watery blisters
Pericarditis - Inflammation of heart
Peripneumonia - Inflammation of lungs
Peritonotis - Inflammation of abdominal area
Petechial fver - Fever characterized by skin spotting

Planet struck- any sudden severe affliction of paralysis
Puerperal exhaustion - Death due to child birth

Puerperal fever- infection after giving birth
Phthiriasis - Lice infestation
Phthisis - Chronic wasting away; a name for tuberculosis
Plague - An acute febrile highly infectious disease with a high fatality rate
Pleurisy - Any pain in the chest area which occurs with each breath; inflammation of the lining of the chest cavity
Podagra - Gout
Poliomyelitis Polio

Pott's disease - Tuberculosis of spine

Potters asthma- Tuberculosis
Puerperal exhaustion - Death due to childbirth
Puerperal fever - Elevated temperature after giving birth to an infant
Puking fever - Milk sickness
Putrid fever - Diphtheria
Quinsy - Tonsillitis

Ragpickers disease- Anthrax
Remitting fever - Malaria
Rheumatism - Any disorder associated with pain in joints
Rickets - Disease of skeletal system

Rising of the lights- croup
Rose cold - Hay fever or nasal symptoms of an allergy
Rubeola - German measles
Sanguineous crust - Scab
Scarlatina - Scarlet fever
Scarlet fever - A disease characterized by red rash
Scarlet rash - Roseola
Sciatica - Rheumatism in the hips
Scirrhus - Cancerous tumors
Scotomy - Dizziness, nausea and dimness of sight

Scouring/ Scours/ Scowering- diarrhea or dysentery
Scrivener's palsy - Writer's cramp
Screws - Rheumatism
Scrofula - Tuberculosis of neck lymph glands. Progresses slowly with abscesses and pistulas develop.

Scrumpox - Skin disease, impetigo
Scurvy - Lack of vitamin C. Symptoms of weakness, spongy gums and hemmoraging under skin
Septicemia - Blood poisoning Shakes - Delirium tremens
Shaking - Chills, ague
Shingles - Viral disease with skin blisters
Ship fever - Typhus
Siriasis - Inflammation of the brain due to sun exposure
Sloes - Milk sickness
Small pox - Contagious disease with fever and blisters
Softening of brain - Result of stroke or hemorrhage in the brain, with result of the tissue softening in affected area
Sore throat distemper - Diphtheria or quinsy
Spanish influenza - Epidemic influenza
Spasms - Sudden involuntary contraction of muscle or group of muscles, similar to a convulsion
Spina bifida - Deformity of spine
Spotted fever - Either typhus or meningitis
Sprue - Tropical disease characterized by intestinal disorders and sore throat
St. Anthony's fire - Also erysipelas, but named so because of affected skin areas are  bright red in appearance
St. Vitas dance - Ceaseless occurrence of rapid complex jerking movements

Stomatitis - Inflammation of the mouth
Stranger's fever - Yellow fever
Strangery - Rupture

Stuffing- Croup
Sudor anglicus - Sweating sickness
Summer complaint - Diarrhea, usually in infants caused by spoiled milk
Sunstroke - Uncontrolled elevation of body temperature due to environment heat. Lack of sodium in the body is a predisposing cause

Surfiet/ Surfet- Vomiting from overeating; gluttony
Swamp sickness - Could be malaria, typhoid or encephalitis
Sweating sickness - Infectious and fatal disease common to UK in 15th century
Tetanus - Infectious fever characterized by high fever, headache, respiratory paralysis, spasms of the muscles, and dizziness
Thrombosis - Blood clot inside blood vessel

Thrush - Childhood disease characterized by spots on mouth, lips and throat; caused by parasitic fungus; often affecting sick, weak, or debilitated individuals or young children

Typhoid/ Typhoid Fever- Severe, often fatal food or water-borne disease; symptoms include sudden onset of sustained fever, severe headache, nausea, loss of appetite, diarrhea.
Tick fever - Rocky Mountain spotted fever

Tissick- Cough
Toxemia of pregnancy - Eclampsia
Trench mouth - Painful ulcers found along gum line, Caused by poor nutrition and poor hygiene
Tussis convulsiva - Whooping cough

Tympany- swelling or tumor
Typhus - Infectious fever characterized high fever, headache, and dizziness; transmitted by lice and fleas
Variola - Smallpox
Venesection Bleeding, generally from injury, but also used as treatment for various diseases
Viper's dance - St. Vitus Dance; chorea; generalized, severe tremors
Water on brain - Enlarged head; hydrocephalus
White swelling - Tuberculosis of the bone
Winter fever - Pneumonia

Wolf- rapidly expanding growth or tumor
Womb fever - Infection of the uterus
Worm fit - Convulsions associated with teething, worms, elevated temperature or diarrhea
Yellowjacket - Yellow fever