vagary

vagary \VAY-guh-ree; vuh-GER-ee\, noun:

An extravagant, erratic, or unpredictable notion, action, or occurrence.

Her words are a dreadful reminder that much of life's consequences are resultant of vagary and caprice, dictated by the tragedy of the ill-considered action, the irrevocable misstep, the irrevocable moment in which a terrible wrong can seem the only right.
-- Rosemary Mahoney, "Acts of Mercy?", New York Times, September 13, 1998

Weather is one of the vagaries of blue-water racing, ruling the sport like a malicious jester.
-- Martin Dugard, Knockdown

This thing called love was a total mystery to me, but the vagaries of passion and despair that accompanied each devotion kept my life in high drama.
-- Jane Alexander, Command Performance

Vagary comes from Latin vagari, "to stroll about, to wander," from vagus, "wandering."