he was a swindler who preyed on gullible elderly widowsSyn:credulous, naive, overtrusting, overtrustful, easily deceived, easily taken in, exploitable, dupable, impressionable, unsuspecting, unsuspicious, unwary, ingenuous, innocent, inexperienced, unworldly, green; informal wet behind the ears, born yesterdayAnt:suspicious••gullible, callow, credulous, ingenuous, naïve, trusting, unsophisticatedSome people will believe anything. Those who are truly gullible are the easiest to deceive, which is why they so often make fools of themselves. Those who are merely credulous might be a little too quick to believe something, but they usually aren't stupid enough to act on it. Trusting suggests the same willingness to believe (a trusting child), but it isn't necessarily a bad way to be (a person so trusting he completely disarmed his enemies). No one likes to be called naïve because it implies a lack of street smarts (she's so naïve she'd accept a ride from a stranger), but when applied to things other than people, it can describe a simplicity and absence of artificiality that is quite charming (the naïve style in which nineteenth-century American portraits were often painted). Most people would rather be thought of as ingenuous, meaning straightforward and sincere (an ingenuous confession of the truth), because it implies the simplicity of a child without the negative overtones. Callow, however, comes down a little more heavily on the side of immaturity and almost always goes hand-in-hand with youth. Whether young or old, someone who is unsophisticated suffers because of lack of experience.
Thesaurus of popular words. 2014.