Hardihood, n.
Etymology: [Hardy + -hood.]
Boldness, united with firmness and constancy of mind; bravery; intrepidity; also, audaciousness; impudence. A bound of graceful hardihood. Wordsworth. It is the society of numbers which gives hardihood to iniquity. Buckminster.
Syn. -- Intrepidity; courage; pluck; resolution; stoutness; audacity; effrontery; impudence.
Shades of meaning
Fernald has no entry of its own for hardihood; he lists it under effrontery, temerity.
Where he writes about it:
Hardihood defies and disregards the rational judgment of men. — from effrontery
Effrontery (L. effrons, barefaced, shameless) adds to audacity and hardihood the special element of defiance of considerations of propriety, duty, and respect for others, yet not to the extent implied in impudence or shamelessness. — from effrontery
We say it is amazing that one should have had the temerity to make a statement which could be readily proved a falsehood, or to make an unworthy proposal to one sure to resent it; in such use temerity is often closely allied to hardihood, audacity, or presumption. — from temerity