If you describe someone as gullible, you mean they are easily tricked because they are too trusting.
例句
What point is there in admitting that the stories fed to the gullible public were false?...承認向輕信媒體的公眾提供了不實報道有何意義呢？I'm so gullible I would have believed him.我很容易上當，可能會相信他的話。
英漢詞典釋義
adj.
易受騙的
The swindlers had roped into a number of gullible persons.騙子們已使一些輕信的人上了當。He’s so gullible he’ll believe anything.他太容易上當,什么事都相信。
英英詞典釋義
Adjective
1. naive and easily deceived or tricked;
"at that early age she had been gullible and in love"