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Lookups spike every year on April 1st. The word really is in the dictionary—promise.

Among the strongest motivations for looking up a word in the dictionary is to prove that someone else is wrong about a word. Another is to answer the question: “is that word really in the dictionary?”


'Gullible' can be traced back to 'gull', a 16th-century word which described either a gullible person (as a noun) or the act of deceiving someone (as a verb).

These two powerful reasons combine on April Fools' Day every year, and we see gullible looked up many times, as the dictionary becomes the punchline of a joke that’s been told and retold but finds new naïve victims every year: "Did you know that gullible isn't in the dictionary?"

This joke is a perfect combination of childish prank and intellectual challenge. The more certain a person is of the answer, the sooner that person wants to prove it—and fall into the trap.

Gullible is a very recent word in English. It dates from the early 1800s, and seems to have been formed from the slightly older gullibility. They trace back to gull, used as both a noun and a verb from the 1500s. The noun meant both “dupe,” “sucker” and “deception,” “fraud” (as in this sentence from Shakespeare: “I should think this a gull but that the white-bearded fellow speaks it.”) Gull as a verb means “to deceive.”

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