Gullibility is a failure of social intelligence in which a person is easily tricked or manipulated into an ill-advised course of action. It is closely related to credulity, which is the tendency to believe unlikely propositions that are unsupported by evidence. Classes of people especially vulnerable to exploitation due to gullibility include children, the elderly, and the developmentally disabled. Meaning The words gullible and credulous are commonly used as synonyms. state that while both words mean "unduly trusting or confiding", gullibility stresses being duped or made a fool of, suggesting a lack of intelligence, whereas credulity stresses uncritically forming beliefs, suggesting a lack of skepticism. states the difference is a matter of degree: the gullible are "the easiest to deceive", while the credulous are "a little too quick to believe something, but they usually aren't stupid enough to act on it." characterize a gullible person as one who is both credulous and naïve. stresses the distinction that gullibility involves an action in addition to a belief, and there is a cause-effect relationship between the two states: "gullible outcomes typically come about through the exploitation of a victim's credulity." Etymology and history The verb to gull and the noun cullibility (with a C) date back to Shakespeare and Swift, whereas gullibility is a relatively recent addition to the lexicon. It was considered a neologism as recently as the early 19th century. The first attestation of gullibility known to the Oxford English Dictionary appears in 1793, and gullible in 1825. The OED gives gullible as a back-formation from gullibility, which is itself an alteration of cullibility. Early editions of Samuel Johnson's A Dictionary of the English Language, including those published in 1797 and 1804, do not contain "gullibility" or "gullible". An 1818 edition by Henry John Todd denounces "gullibility" as "a low expression, sometimes used for cullibility". Gullibility does not appear in Noah Webster's 1817 A dictionary of the English language, but it does appear in the 1830 edition of his American dictionary of the English language, where it is defined: "n. Credulity. (A low word)". Both gullibility and gullible appear in the 1900 New English Dictionary. Examples presents dozens of examples of gullibility in literature and history: In the fairy tale The Adventures of Pinocchio, the title character is a gullible puppet who is repeatedly duped by other characters; part of his transformation into a human being is learning to avoid