What is the Plural for Diagnosis? Determining the Correct Plural

3 min readFeb 23, 2024

In the world of medical terms, understanding plurals can sometimes be tricky, and the word “diagnosis” is no exception. When we talk about more than one diagnosis, what is the correct way to say it? In this article, we will explore the plural for “diagnosis” and unravel the mystery behind using the right plural in simple and clear terms.

What does Diagnosis mean?
Diagnosis is a term used in medicine to figure out what’s going on with someone’s health. It’s like solving a puzzle to identify an illness or condition. Doctors use various methods, such as asking about symptoms, doing tests, or examining the body, to make a diagnosis. Once they understand what’s causing the health issue, they can decide on the best way to help and treat the person. In simple terms, diagnosis is like finding answers about someone’s health puzzle so that they can get the right care.

Diagnosis: Singular and Plural

The singular form of “diagnosis” is used when referring to one instance of identifying a health issue, while the plural for “diagnosis” is “diagnoses” (replacing “i” with “e”) and is used when talking about multiple instances or various health conditions. So, it’s “diagnosis” for one and “diagnoses” for more than one.

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Singular and Plural usage in Sentences

Singular Usage

The nurse awaited the doctor’s official diagnosis before discussing treatment options.
Getting a timely and accurate diagnosis is crucial for effective medical intervention.
He sought a second opinion after receiving an unexpected diagnosis from his primary care physician.
The specialist offered a detailed and insightful diagnosis after reviewing the patient’s medical history.

Plural Usage

The conference addressed various diagnostic challenges faced by healthcare professionals.
Doctors often collaborate to share their experiences with different diagnoses to improve patient care.
The hospital’s database contains thousands of diverse diagnoses encountered over the years.
Researchers are studying the commonalities among multiple diagnoses to advance medical knowledge and treatment approaches.

Why the Plural of Diagnosis is “Diagnoses”?

The plural form of “diagnosis” is “diagnoses” due to the word’s Greek origin. In Greek, “diagnosis” is a singular noun, and when converting it to English, the standard practice is to add “es” to form the plural. This linguistic rule maintains consistency with other words of Greek origin in the English language. Therefore, when referring to more than one health assessment or medical determination, we use “diagnoses” to indicate the plural form, aligning with the conventions of English grammar and etymology.

Some other Words and their Plurals

1. Analysis (Singular) — Analyses (Plural)

The scientist conducted a thorough analysis of the data.
Multiple analyses were performed to ensure the accuracy of the results.

2. Basis (Singular) — Bases (Plural)

The argument was built on a solid basis of facts.
The team considered various bases for their decision.

3. Criterion (Singular) — Criteria (Plural)

The school has specific criteria for selecting scholarship recipients.
Several criteria must be met to qualify for the program.

4. Focus (Singular) — Foci (Plural)

The photographer adjusted the camera’s focus for a clear shot.
The foci of the study included both environmental and social factors.

5. Thesis (Singular) — Theses (Plural)

She spent months researching and writing her thesis.
Many theses on the topic have been published in academic journals.

6. Index (Singular) — Indices (Plural) or Indexes (Plural)

The book’s index made it easy to find specific information.
The indices of economic growth were carefully analyzed.

7. Phenomenon (Singular) — Phenomena (Plural)

The unusual event was considered a rare phenomenon.
Scientists observed various phenomena during the experiment.

8. Crisis (Singular) — Crises (Plural)

The country faced an economic crisis in the aftermath of the recession.
Governments must develop strategies to address multiple crises.

Remember that irregularities exist, and not all words follow the same pattern when forming plurals in English.