Plural of Diagnosis: Meaning, Rules, and Examples

The plural of diagnosis is a common point of confusion in English, especially for those learning medical or academic writing. While the singular form diagnosis describes the identification of a condition, the plural form of diagnosis changes its spelling and pronunciation due to its Greek and Latin origin. This article explains the diagnoses plural, why it is an irregular plural in English, and how to use it correctly in sentences. By the end, you’ll understand the full diagnosis meaning, the rules behind its change, and how it compares to other Greek and Latin plurals.

Medical Terms Ending in -is

Word	Meaning	Example
Diagnosis → Diagnoses	Identification of a disease	The diagnoses were confirmed after lab tests.
Prognosis → Prognoses	Prediction of disease outcome	The doctor gave two possible prognoses.
Analysis → Analyses	Detailed examination	His analyses of the symptoms were thorough.
Hypothesis → Hypotheses	Proposed explanation	Several hypotheses were tested in the lab.
Crisis → Crises	Time of great difficulty	Multiple crises hit the hospital in winter.
Synthesis → Syntheses	Combination of elements	The scientist’s syntheses improved treatment.
Paralysis → Paralyses	Loss of muscle function	The injury caused multiple paralyses.
Psychosis → Psychoses	Severe mental disorders	The patient had recurring psychoses.
Thesis → Theses	Research paper	The students presented their theses.
Oasis → Oases	Fertile spot in desert	We found several oases during the trip.

Common Scientific Plural Forms

Word	Meaning	Example
Symbiosis → Symbioses	Mutual living relationship	The coral and algae have symbioses.
Metamorphosis → Metamorphoses	Change of form	Butterflies go through metamorphoses.
Necrosis → Necroses	Death of tissue	The scans showed several necroses.
Cirrhosis → Cirrhoses	Liver disease	He treated many cirrhoses last year.
Mycosis → Mycoses	Fungal infection	Doctors treated five mycoses cases.
Prognathis → Prognathes	Extended jaw condition	Some prognathies require surgery.
Stenosis → Stenoses	Narrowing of body passage	Multiple stenoses were found in arteries.
Hypnosis → Hypnoses	State of focused attention	Different hypnosis techniques were studied.
Fibrosis → Fibroses	Thickening of tissue	Two fibroses affected his lungs.
Apoptosis → Apoptoses	Programmed cell death	The research studied apoptoses in cancer cells.

Grammar Rules for Words Ending in -is

Word	Meaning	Example
Prognathis → Prognathes	Extended jaw	The dentist studied cases of prognathes.
Scoliosis → Scolioses	Curvature of the spine	Several scolioses were corrected by surgery.
Dermatosis → Dermatoses	Skin disorder	Summer heat worsened dermatoses.
Tuberculosis → Tuberculoses	Bacterial lung infections	Doctors treated multiple tuberculosis.
Osteoporosis → Osteoporoses	Weak bones	Women are more prone to osteoporoses.
Cyanosis → Cyanoses	Blue discoloration of skin	Heart issues caused cyanoses in newborns.
Psychoneurosis → Psychoneuroses	Emotional disorders	The clinic reported five psychoneuroses.
Halitosis → Halitoses	Bad breath	Dental care helped with halitoses.
Adenosis → Adenoses	Gland disease	Lab tests showed adenoses in samples.
Angiogenesis → Angiogeneses	Formation of blood vessels	Cancer research targets angiogeneses.

Plurals in Science and Medicine

Word	Meaning	Example
Arthrosis → Arthroses	Joint degeneration	Elder patients suffer from arthroses.
Leukocytosis → Leukocytoses	High white blood cells	The report listed leukocytoses in patients.
Sepsis → Sepses	Severe infection	Hospitals try to prevent sepsis.
Myelosis → Myeloses	Spinal cord disease	Rare myeloses were studied in neurology.
Epiphysis → Epiphyses	End of long bones	Growth plates are found in epiphyses.
Synapsis → Synapses	Cell pairing	Genetics research explains synapses.
Trichinosis → Trichinoses	Worm infection	Pork caused several trichinoses outbreaks.
Endometriosis → Endometrioses	Uterine tissue disorder	Women with endometrioses often need surgery.
Leukosis → Leukoses	White blood cell disease	Farm animals had leukoses.
Papillomatosis → Papillomatoses	Wart growth	Papillomatoses may affect skin and throat.

Words from Biology and Zoology

Word	Meaning	Example
Mitosis → Mitoses	Cell division	Scientists observed multiple mitoses.
Meiosis → Meioses	Cell reproduction	Meioses occur in reproductive cells.
Cytolysis → Cytolyses	Cell destruction	Toxins can cause cytolyses.
Hemolysis → Hemolyses	Blood cell destruction	Certain drugs cause hemolyses.
Proteolysis → Proteolyses	Protein breakdown	Digestion involves proteolyses.
Phagocytosis → Phagocytoses	Cell engulfing particles	Immune cells perform phagocytoses.
Osmosis → Osmoses	Water movement in cells	Plants rely on osmoses for hydration.
Trophozoite → Trophozoites	Active parasite stage	Doctors found trophozoites in blood.
Apomixis → Apomixes	Asexual reproduction	Some plants use apomixes to spread.
Sympathectomy → Sympathectomies	Nerve removal surgery	Sympathectomies help treat excessive sweating.

Plurals in Chemistry and Physics

Word	Meaning	Example
Catalysis → Catalyses	Speeding chemical reaction	Enzymes act as catalyses.
Electrolysis → Electrolyses	Breaking down with electricity	Electrolyses separate water into gases.
Photolysis → Photolyses	Light-driven breakdown	Plants perform photolyses during photosynthesis.
Hydrolysis → Hydrolyses	Reaction with water	Hydrolyses occur in digestion.
Pyrolysis → Pyrolyses	Decomposition by heat	Wood undergoes pyrolyses.
Hemodialysis → Hemodialyses	Blood filtering	Patients need regular hemodialysis.
Dialysis → Dialyses	Separation process	The lab performed multiple dialyses.
Thermogenesis → Thermogeneses	Heat production	Thermogeneses happen in mammals.
Lithogenesis → Lithogeneses	Rock formation	Geology studies lithogeneses.
Morphogenesis → Morphogeneses	Shape formation in biology	Morphogeneses occur in embryo growth.

Geology and Earth Science Terms

Word	Meaning	Example
Hypothesis → Hypotheses	Proposed theory	Scientists tested several hypotheses.
Parenthesis → Parentheses	Bracket punctuation	The equation used two parentheses.
Genesis → Genesises	Beginning or origin	Several genesises of ideas were discussed.
Crisis → Crises	Difficult times	Two crises affected the town.
Axis → Axes	Central lines	The chart had two axes.
Oasis → Oases	Desert water spot	Camels rested at oases.
Basis → Bases	Foundations	The research had strong bases.
Synopsis → Synopses	Summaries	The teacher read the synopses.
Thesis → Theses	Academic research papers	Students defended their theses.
Analysis → Analyses	Examinations	Multiple analyses confirmed the results.

Latin and Greek Influence on Medical Plurals

Word	Meaning	Example
Prosthesis → Prostheses	Artificial body part	Doctors fitted new prostheses.
Diagnosis → Diagnoses	Disease identification	Three diagnoses matched the symptoms.
Hypothesis → Hypotheses	Proposed ideas	The hypotheses were tested in trials.
Psychosis → Psychoses	Mental illness	The clinic handled many psychoses.
Prognosis → Prognoses	Expected disease outcome	Early prognoses were positive.
Parenthesis → Parentheses	Brackets	The code used parentheses.
Paralysis → Paralyses	Loss of movement	Injury caused paralysis in limbs.
Synthesis → Syntheses	Combination of ideas	The report gave syntheses of findings.
Metamorphosis → Metamorphoses	Life form change	Frogs undergo metamorphoses.
Symbiosis → Symbioses	Mutual benefit	Plants and fungi have symbioses.

Rare and Specialized Scientific Plurals

Word	Meaning	Example
Anthracosis → Anthracoses	Lung disease from coal dust	Miners had anthracoses.
Sarcoidosis → Sarcoidoses	Inflammatory disease	Doctors diagnosed several sarcoidoses.
Lymphadenosis → Lymphadenoses	Lymph node disease	The scan showed lymphadenoses.
Fibromatosis → Fibromatoses	Tissue overgrowth	Surgery removed fibromatoses.
Angiomatosis → Angiomatoses	Blood vessel tumors	Rare angiomatoses affect organs.
Lipomatosis → Lipomatoses	Fat growths	Lipomatoses can be benign or harmful.
Myomatosis → Myomatoses	Muscle tumors	Doctors studied myomatoses in patients.
Papillomatosis → Papillomatoses	Wart growth	Throat papillomatoses need treatment.
Osteochondrosis → Osteochondroses	Bone-cartilage disease	Athletes risk osteochondroses.
Mastocytosis → Mastocytoses	Mast cell buildup	The hospital researched mastocytoses.

Plural of Diagnosis in Medicine

Word	Meaning	Example Sentence
Syndromes → Syndromes	A group of symptoms indicating a condition	The doctor noted several syndromes in his report.
Illness → Illnesses	A state of poor health	Seasonal changes bring various illnesses.
Infection → Infections	The invasion of the body by pathogens	The hospital reported multiple infections after surgery.
Treatment → Treatments	Methods to cure or manage diseases	The clinic offers several treatments for diabetes.
Symptom → Symptoms	A sign or indicator of a disease	Fever and cough are common symptoms of flu.
Therapy → Therapies	Medical treatment for physical or mental conditions	Different therapies help patients recover faster.
Injury → Injuries	Damage to body tissues	The athlete suffered multiple injuries during the match.
Condition → Conditions	A particular state of health	Patients with chronic conditions require regular check-ups.
Complication → Complications	Secondary issues caused by a primary disease	Surgery can sometimes lead to complications.
Prognosis → Prognoses	A forecast of the disease’s course	The prognoses for cancer patients vary widely.

Plural of Diagnosis in Pathology

Word	Meaning	Example Sentence
Biopsy → Biopsies	Examination of tissue to detect disease	The lab processed several biopsies today.
Lesion → Lesions	Damaged area of tissue or organ	The MRI revealed multiple lesions on the liver.
Tumor → Tumors	Abnormal growth of cells	The hospital treats both benign and malignant tumors.
Specimen → Specimens	A sample for testing	The lab received blood specimens for analysis.
Culture → Cultures	Growth of microorganisms in a lab	The test required bacterial cultures for diagnosis.
Mutation → Mutations	A change in DNA sequence	Cancer can result from genetic mutations.
Infarction → Infarctions	Tissue death due to lack of blood supply	Heart infarctions require urgent care.
Pathogen → Pathogens	Disease-causing organisms	Hospitals work to control dangerous pathogens.
Ulcer → Ulcers	Open sores on skin or internal tissue	Stress can cause stomach ulcers.
Plaque → Plaques	Deposits in arteries or on teeth	Arterial plaques can block blood flow.

Psychology in Plural of Diagnosis

Word	Meaning	Example Sentence
Disorder → Disorders	Mental or emotional health conditions	Anxiety and depression are common disorders.
Phobia → Phobias	Irrational fears	Many people have multiple phobias.
Addiction → Addictions	Dependency on substances or behaviors	Addictions can harm physical and mental health.
Hallucination → Hallucinations	Perception without real stimulus	Sleep deprivation can cause hallucinations.
Delusion → Delusions	Strong false beliefs	Schizophrenia often involves delusions.
Impulse → Impulses	Sudden urges	Strong emotional impulses can affect decision-making.
Mood → Moods	Emotional states	Therapy helps regulate negative moods.
Stress → Stresses	Mental or emotional strain	Chronic stresses can weaken immunity.
Trauma → Traumas	Deep emotional or physical injury	War veterans often suffer from traumas.
Personality → Personalities	Unique psychological traits	Siblings can have very different personalities.

Plural of Diagnosis in Veterinary Science

Word	Meaning	Example Sentence
Breed → Breeds	Types of animals within a species	The farm keeps several breeds of cattle.
Parasite → Parasites	Organisms living off a host	Dogs must be treated for parasites regularly.
Allergy → Allergies	Immune reactions to substances	Cats can develop food allergies.
Vaccination → Vaccinations	Immunization against diseases	Puppies require multiple vaccinations.
Inoculation → Inoculations	Introducing a vaccine into the body	Farmers schedule animal inoculations annually.
Infection → Infections	Disease caused by germs	Birds can get respiratory infections.
Condition → Conditions	Health state of an animal	The vet monitors chronic conditions in older pets.
Symptom → Symptoms	Signs of illness	Lethargy and loss of appetite are symptoms in dogs.
Treatment → Treatments	Methods of healing or curing	The clinic offers advanced treatments for livestock.
Diagnosis → Diagnoses	Identifying a disease	The vet made several diagnoses after examining the herd.

Conclusion

The plural of diagnosis is diagnoses, an example of irregular plurals in English that come from Greek and Latin roots. This rule is shared by other medical terms such as the plural of analysis and plural of crisis. Knowing the difference between diagnosis vs diagnoses is essential for correct diagnosis grammar and clear communication. By practicing diagnosis examples and diagnoses examples, you can confidently use the correct form in both professional and everyday language.