Venturesome, a. — Webster enters it under “venturesome”
Inclined to venture; not loth to run risk or danger; venturous; bold; daring; adventurous; as, a venturesome boy or act. -- Ven"ture*some*ly, adv. -- Ven"ture*some*ness, n.
Shades of meaning
Fernald has no entry of its own for venturesomeness; he lists it under temerity.
Where he writes about it:
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. — from temerity