candour
Concise Oxford English Dictionary © 2008 Oxford University Press:
candour /ˈkandə(r)/ (US candor)
▶noun the quality of being open and honest.
– origin ME (in the sense ‘whiteness’, hence ‘purity’, ‘lack of bias’, ‘honesty’): from L. candor.
'candour' also found in these Oxford entries:

