I must admit I am an avowed "dictionariaholic." It is not a word you will find in the dictionary -- I made it up for my condition -- I collect large, oversized, multiple volume dictionaries. I find endless pleasure opening up to a random page to find a new word.
I know writers who don't have dictionaries and rely on "Spellcheck." What they don't realise is: if the word is not spelled incorrectly, Spellcheck won't flag it. And, if you use the improper word, you are the one who looks idiotic.
So, here is a little writer's helper for those of you who may be writing fiction with a medical theme.
Diagnosis: the act of deciding, on the basis of analyzing symptoms, what disease is affecting the patient. It comes, like most medical language, from Greek, specifically from dia (between) and gignoskein (to know).
Prognosis: the prediction made by a physician of the course and probable termination of the disease. It has the same root as diagnosis, of course, and the prefix pro means "before." Thus a prognosis is a "knowing before" -- or prediction.
The next time you are out at a flea market or yard sale, look for a lovely old dictionary -- you just might get hooked.