Understanding Medical Grammar: How do you say the plural of diagnosis?

According to linguists, the English language is rich with irregular plurals, many of which are derived from classical Greek and Latin.

So, how do you say the plural of diagnosis? Correctly pronouncing and writing this word is key to clear communication in medical contexts.

Quick Summary

The plural form of the singular noun diagnosis is diagnoses, and it is pronounced 'dahy-uhg-noh-seez.' This is not a mistake but an application of an ancient Greek rule retained in many English medical terms, where '-is' becomes '-es.'

Key Points

• Plural Form: The plural of diagnosis is diagnoses, not 'diagnosises'.

• Pronunciation: The plural diagnoses is pronounced 'dahy-uhg-noh-seez,' with a 'z' sound.

• Greek Origin: The irregular plural rule comes from the word's Greek origin, where nouns ending in '-is' change to '-es' in the plural.

• Context is Key: Use diagnosis for a single instance and diagnoses for multiple instances.

• Professional Impact: Using the correct plural form demonstrates accuracy and professionalism in medical and academic settings.

The Correct Plural: Diagnoses

The correct plural form of diagnosis is diagnoses. The change from '-is' to '-es' is a standard rule for many English words borrowed directly from ancient Greek. Unlike common English nouns that simply add an 's' or 'es' to form their plural, words like diagnosis follow an older, more complex linguistic pattern. This makes it a classic irregular plural noun that requires specific attention to detail, especially in formal or clinical writing.

The Greek Origin of Irregular Plurals

To understand why diagnosis becomes diagnoses, you must look to its Greek roots. The word is derived from the Greek diágnōsis, meaning 'a distinguishing' or 'to know thoroughly.' When the word was adopted into New Latin and subsequently into English, it retained its original pluralization rule. This same pattern is seen in a number of other scientific and medical terms, reinforcing its use in a professional setting. Recognizing this pattern helps unlock the plurals of other related words, making it a valuable piece of knowledge for anyone in the medical field.

Mastering the Pronunciation

Proper pronunciation is just as important as correct spelling. The singular diagnosis is pronounced 'dahy-uhg-noh-sis' (often with a soft 's' sound). The plural diagnoses shifts to 'dahy-uhg-noh-seez' (with a hard 'z' sound at the end). This change in sound is the result of the spelling change. Paying attention to this subtle shift ensures you sound professional and accurate when speaking about multiple medical conditions or assessments.

Diagnosis vs. Diagnoses: When to Use Which

Knowing when to use the singular vs. the plural form depends entirely on context. Here are some simple guidelines:

• Use diagnosis when referring to a single determination. For example: "The doctor gave a clear diagnosis of influenza."
• Use diagnoses when referring to more than one determination. For example: "The patient's chart listed multiple diagnoses, including diabetes and high blood pressure."

Practical Examples in Sentences

• Singular: The radiologist's initial diagnosis pointed to a fractured rib.
• Plural: A differential diagnoses list was created to narrow down the possibilities.
• Plural: Over the course of her career, Dr. Alistair has made countless diagnoses.
• Singular: Getting a swift diagnosis is crucial for early treatment.
• Plural: A team of specialists worked together to confirm all the patient's diagnoses.

Comparison: Singular vs. Plural Medical Terms

This table illustrates how other Greek and Latin-derived medical terms follow a similar irregular pluralization rule.

Singular	Plural	Rule	Example Context
Analysis	Analyses	-is to -es	We performed several analyses of the blood work.
Crisis	Crises	-is to -es	The team is prepared for multiple health crises.
Thesis	Theses	-is to -es	Her research focused on three different theses.
Bacterium	Bacteria	-um to -a	He studied the different types of bacteria in the soil.
Vertebra	Vertebrae	-a to -ae	The patient had several fractured vertebrae.

Avoiding Common Pluralization Errors

One of the most common mistakes is trying to apply the standard English pluralization rule by adding an 's' to the word, resulting in the incorrect form, 'diagnosises'. This error is easily avoided by remembering the word's Greek origins and its special rule. Another error is using the plural form when only a single diagnosis is being discussed, or vice-versa. Always check the context to ensure the number of diagnoses being referred to is consistent with the grammatical form you are using.

The Importance of Precision in Medical Communication

In a field as critical as health and medicine, precise language is paramount. Using the correct singular and plural forms, such as distinguishing between diagnosis and diagnoses, avoids ambiguity and potential for error. Whether in medical documentation, a research paper, or a conversation with a colleague, using the correct terminology demonstrates a high level of expertise and attention to detail. This linguistic accuracy is a foundational component of professional communication and patient safety.

Other Irregular Medical Plurals

Beyond diagnosis, the medical field is full of irregular plurals. Here are a few more to help expand your vocabulary:

• Focus: The plural of this Latin-derived word can be either foci (the traditional plural) or focuses (the anglicized plural).
• Appendix: In anatomy, the plural is appendices, while in publishing, it is more often appendixes.
• Cortex: The plural is cortices.

Understanding these nuanced rules ensures you are not only grammatically correct but also culturally competent within the medical community. For more information on complex word origins and plurals, consult authoritative resources like the Merriam-Webster dictionary, a widely respected source for etymology and usage.

Conclusion

To correctly answer how do you say the plural of diagnosis?, remember that the plural is diagnoses due to its Greek linguistic heritage. Mastering this irregular plural, along with others like crises and analyses, demonstrates a command of language that is highly valued in the medical and scientific communities. Accurate and precise communication, down to the spelling and pronunciation of medical terms, is a hallmark of professional competence in healthcare.

Frequently Asked Questions

Is 'diagnosises' a real word?

No, 'diagnosises' is not a real or grammatically correct word. It is a common error resulting from applying standard English pluralization rules to an irregularly pluralized word of Greek origin. The correct plural is diagnoses.

How do you remember the correct plural of diagnosis?

A helpful trick is to remember other words that follow the same pattern, such as crisis becoming crises. The rule is: if a word ends in '-is' and comes from Greek, the plural is likely '-es.' A simple memory cue is to associate the 'e' sound in 'diagnoses' with the idea of 'many' diagnoses.

Does the pronunciation of 'diagnosis' and 'diagnoses' change?

Yes, the pronunciation changes. The singular form, diagnosis, ends with a soft 's' sound. The plural form, diagnoses, ends with a hard 'z' sound, reflecting the change in the word's ending from '-is' to '-es'.

Why do some medical words have irregular plurals?

Many medical terms, like diagnosis, were borrowed directly from ancient Greek or Latin. In many cases, English retained the original pluralization rules from these classical languages, creating exceptions to modern English grammar rules.

Are there other medical words that follow the same plural rule?

Yes, several other medical and scientific terms follow this rule. Examples include analysis (analyses), crisis (crises), thesis (theses), and prognosis (prognoses).

When would a patient have multiple 'diagnoses'?

A patient might have multiple diagnoses if they suffer from more than one medical condition at the same time. For instance, a patient could have diagnoses of both arthritis and asthma.

Is it acceptable to use 'diagnosises' in casual conversation?

While some might understand what you mean, it is not grammatically correct and is considered unprofessional, even in casual conversation. Using the correct term, diagnoses, is always best practice to ensure clarity and accuracy.