Capricious

When:

Lookups spiked on March 11, 2013.

Why:

A judge blocked NYC Mayor Michael Bloomberg's proposed ban on large sugary drinks, saying that its enforcement would have been "arbitrary and capricious." The judge noted that restaurants and movie theaters would be affected by the ban, but convenience stores wouldn't be.

Capricious means "changing often and quickly" or "not logical or reasonable."

It comes from the French word caprice, which means "a sudden, impulsive, and seemingly unmotivated notion or action." Caprice originates in capriccio, an Italian word meaning "a whim" or "a fancy" - and which can also describe a piece of classical music set at a fast tempo.