How do you define a bug/defect?
Few easy and most used ones -
"A defect is deviation or discrepancy in observed behavior of the software with reference to an authoritative source of reference" or simply "deviation from specification"
"A crash, loss of data, illegal access, slow response, cluttered GUI, bad aesthetics etc are bugs"
"An error or fault or failure in the system"
"A coding error"
"A mistake committed by the developer"
"A undocumented feature"
"An expected behavior that negatively impacts the user"
What is your definition?