Plural of Diagnosis

The word “diagnosis” holds significant weight in both medical and everyday language. Often used in clinical contexts, it also permeates general conversation, symbolizing the act of identifying a problem or cause. This term, derived from Greek origins, has a unique plural form that sometimes causes confusion, especially for those learning English or not regularly engaged in medical or technical discourse.

The Singular and Plural of Diagnosis

In its singular form, the word is “diagnosis.” However, when it comes to pluralization, “diagnosis” follows a less common pattern in English, adopting the plural form “diagnoses.” This transformation is indicative of its Greek roots, where nouns ending in “-is” often change to “-es” in their plural forms.

plural of diagnosis

Understanding Diagnosis


"Diagnosis" refers to the identification of the nature and cause of something, typically a disease or condition, through examination. In a broader sense, it can also mean the analysis of the underlying nature of a situation or issue.


The term is predominantly used in medical contexts but is also applicable in mechanics, science, and even in everyday problem-solving scenarios.


From Greek “diagnosis,” meaning “discernment, distinguishing,” from “diagignoskein,” meaning “to distinguish, discern.”

In various contexts, “diagnosis” can refer to the process of determining a condition or the conclusion reached through that process.

Examples of Diagnosis in Sentences

  1. Medical Context: “The doctor made an accurate diagnosis of the patient’s condition after reviewing the test results.”
  2. Multiple Cases: “After reviewing several patients, the team documented varying diagnoses, ranging from common allergies to more complex autoimmune disorders.”
  3. Non-Medical Scenario: “The mechanic’s diagnosis of the car’s issue was a faulty transmission.”
  4. Figurative Use: “Her keen diagnosis of the company’s financial problem saved them from bankruptcy.”
  5. Comparative Discussion: “Comparing the diagnosis of similar symptoms can lead to better treatment strategies in medical research.”

Common Mistakes and Confusions

  1. Misuse of Plural Form: Using “diagnosises” instead of the correct “diagnoses“.
  2. Confusing with Prognosis: Mixing up “diagnosis” (identifying the problem) with “prognosis” (predicting the course of a condition).
  3. Overgeneralisation: Assuming “diagnosis” is only applicable in medical contexts, ignoring its broader usage.
  4. Pronunciation: “Diagnosis” is pronounced as /daɪ.əɡˈnoʊ.sɪs/, while “diagnoses” is /daɪ.əɡˈnoʊ.siːz/.
  5. Misuse in Singular Context: Using “diagnoses” for a single case is incorrect. It’s important to match the number to the form used.

Commonly Asked Questions

  1. Can “diagnosis” be pluralized as “diagnosises”?
    • No, the correct plural form is “diagnoses.
  2. How do I know when to use “diagnosis” or “diagnoses”?
    • Use “diagnosis” for a single case and “diagnoses” for multiple cases.
  3. Does the meaning change in the plural form?
    • No, the meaning remains the same, though the plural form refers to multiple instances.


Understanding the correct plural form of “diagnosis” is crucial, especially in professional settings. The transition from “diagnosis” to “diagnoses” is a classic example of how English borrows and transforms words from other languages, in this case, Greek. Recognizing and using the correct plural forms enriches language proficiency and ensures clarity in communication.

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