The noun diagnosis refers to the process of analyzing information to understand or explain something. (The plural of diagnosis is diagnoses.)
The noun prognosis means a forecast or prediction. (The plural of prognosis is prognoses.)
Examples:
- Medical researchers are examining strategies for the early diagnosis of Alzheimer's disease.
- The prognosis for continued and sustainable improvements in human well-being on our planet is, at best, guarded.
Practice:
(a) When the ship's engine wouldn't start, the chief engineer offered a _____ of the problem.
(b) The gloomy _____ for jobs and incomes in the coming year sent stock prices falling.
