When:
Lookups spiked on November 1, 2011.
Why:
World financial markets were thrown into confusion when the Greek Prime Minister announced a surprise decision to hold a referendum on the bailout conditions offered by eurozone countries.
Referendum means "a public vote on a particular issue" and comes from the Latin verb that means "to refer."
(Later in the week, the referendum was cancelled after all.)
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Merriam-Webster unabridged