Prognosis vs. Diagnosis: What’s the Difference?

Medical professionals use a language that might seem only distantly related to everyday English. If you’ve ever glanced at a physician’s notepad, the incomprehensible scribbles and glyphs contained therein would seem to support this notion.

Be that as it may, medical terms have specific meanings, and it’s important not to confuse them. Even setting aside any concerns about the careful and correct use of language, to do so could put your own health at risk.

Diagnosis and prognosis, two of the most easily confused pieces of medical terminology, have related but separate meanings. Next time you see your doctor or visit a clinic, you can impress the practitioner who serves you by knowing what these meanings are, and what they mean for your health.

What is the Difference Between Prognosis and Diagnosis?

In this article, I will compare prognosis and diagnosis. I will use each word in an example sentence to properly illustrate its meaning.

Plus, I will tell you a memory trick that should help you remember whether you mean prognosis or diagnosis, depending on the context of your writing.

When to Use Diagnosis

Definition of diagnosis definition and definition of prognosis definitionWhat does diagnosis mean? Diagnosis is a noun. It means an identification of a condition by observation of symptoms. It is usually reserved for medical or psychological contexts.

For example,

  • A diagnosis of ADHD allows families access to a wider range of funding and services.
  • “I have examined the tissue samples, and my diagnosis is cancer,” the doctor told Miriam.
  • The Samsung announcement came after the company suspended production of the Note 7, a decision that raised questions about Samsung’s initial diagnosis of the problem, which attributed overheating batteries in some Note 7s to manufacturing issues at one of its suppliers. –The Wall Street Journal

When to Use Prognosis

Define diagnosis and define prognosisWhat does prognosis mean? Prognosis is also a noun. A prognosis refers to a prediction of the course and outcomes of a condition. Thus, once a professional observes symptoms and makes a diagnosis, she might then make a prognosis based on the likely trajectory of an illness.

For example,

  • Research shows that the prognosis for an untreated gunshot wound includes internal bleeding, infection, organ failure, and death.
  • “I do not have enough information on this type of cancer to make an accurate prognosis,” the doctor continued.
  • Chiefs coach Andy Reid called the prognosis of Jamaal Charles “all positive” on Wednesday, increasing the likelihood that the injured running back finally will get on the field this weekend. –The Washington Post

Trick to Remember the Difference

prognosis versus diagnosisHere is a helpful trick to remember diagnosis vs. prognosis. Both words are nouns that refer to medical or psychiatric conditions.

  • Use diagnosis for an identification of someone’s current condition.
  • Use prognosis for that condition’s implications for future health.

If you remember that prognosis and prediction each begin with the letter P, you can remember that a prognosis refers to the way an illness or condition might progress in the future.

A diagnosis, meanwhile, refers to a person’s health today. Diagnosis and today are each spelled with the letter D, making these two words just as easy to link.

Whether you are writing about a prognosis or diagnosis, these tricks will help you choose the right word every time.


Is it prognosis or diagnosis? Medical terminology is complex, and at times difficult to understand. It contains jargon and many words which are not part of everyday English.

Prognosis and diagnosis are two words used to describe a person’s illness or condition.

  • A prognosis refers to how a current condition could be expected to affect a person’s health in the future.
  • Diagnosis refers to a condition in the present, informed by observation of current symptoms.

In other words, a prognosis is a prediction. Prediction and prognosis are each spelled with a P, which is a great trick to help you remember what the word prognosis means.