What is the plural of 'prognosis'?

The correct plural form of 'prognosis' is 'prognoses.' This follows the standard rule in English for forming plurals of words that end with the suffix '-is,' which typically changes to '-es' in the plural form. The word 'prognosis' is derived from Greek, where similar suffix changes occur. Thus, when referring to multiple instances of a prognosis, the appropriate term used is 'prognoses.'

Other variations such as 'prognosies,' 'prognoseos,' and 'prognosises' do not conform to English language conventions for pluralization and are not recognized as correct by standard English grammar rules. This reinforces the importance of understanding specific linguistic rules when dealing with medical terminology.