Definition of diagnosis noun from the Oxford Advanced Learner's Dictionary

diagnosis

noun
ˌdaɪəɡˈnəʊsɪs
 
; ˌdaɪəɡˈnoʊsɪs
 
[countable, uncountable] plural diagnoses
ˌdaɪəɡˈnəʊsiːz
 
; ˌdaɪəɡˈnoʊsiːz
 
 
diagnosis (of something) the act of discovering or identifying the exact cause of an illness or a problemdiagnosis of lung cancerThey are waiting for the doctor's diagnosis.An accurate diagnosis was made after a series of tests.