diffidence
Concise Oxford English Dictionary © 2008 Oxford University Press:
diffident/ˈdɪfɪdənt/
▶adjective modest or shy because of a lack of self-confidence.
– derivatives
diffidence noun,
diffidently adverb.
diffidence noun,
diffidently adverb.
– origin ME: from L. diffident-, diffidere ‘fail to trust’.
'diffidence' also found in these Oxford entries:

