Source : Webster's Revised Unabridged Dictionary (1913)

Temerity \Te*mer"i*ty\, n. [L. temeritas, from temere by chance,
   rashly; perhaps akin to Skr. tamas darkness: cf. F.
   t['e]m['e]rit['e].]
   Unreasonable contempt of danger; extreme venturesomeness;
   rashness; as, the temerity of a commander in war.

   Syn: Rashness; precipitancy; heedlessness; venturesomeness.

   Usage: {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.

Source : WordNet®

temerity
     n : fearless daring [syn: {audacity}, {audaciousness}]