Temerity, n.
Etymology: [L. temeritas, from temere by chance, rashly; perhaps akin to Skr. tamas darkness: cf. F. témérité.]
Unreasonable contempt of danger; extreme venturesomeness; rashness; as, the temerity of a commander in war.
Syn. -- Rashness; precipitancy; heedlessness; venturesomeness. -- Temerity, Rashness. These words are closely allied in sense, but have a slight difference in their use and application. Temerity is Latin, and rashness is Anglo-Saxon. As in many such cases, the Latin term is more select and dignified; the Anglo-Saxon more familiar and energetic. We show temerity in hasty decisions, and the conduct to which they lead. We show rashness in particular actions, as dictated by sudden impulse. It is an exhibition of temerity to approach the verge of a precipice; it is an act of rashness to jump into a river without being able to swim. Temerity, then, is an unreasonable contempt of danger; rashness is a rushing into danger from thoughtlessness or excited feeling. It is notorious temerity to pass sentence upon grounds uncapable of evidence. Barrow. Her rush hand in evil hour Forth reaching to the fruit, she plucked, she eat. Milton.
Shades of meaning
Rashness applies to the actual rushing into danger without counting the cost; temerity denotes the needless exposure of oneself to peril which is or might be clearly seen to be such. Rashness is used chiefly of bodily acts, temerity often of mental or social matters; there may be a noble rashness, but temerity is always used in a bad sense. 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. Venturesomeness dallies on the edge of danger and experiments with it; foolhardiness rushes in for want of sense, heedlessness for want of attention, rashness for want of reflection, recklessness from disregard of consequences. Audacity, in the sense here considered, denotes a dashing and somewhat reckless courage, in defiance of conventionalities, or of other men's opinions, or of what would be deemed probable consequences; as, the audacity of a successful financier. Compare effrontery.