Simpleton (noun)

1. A person who is easy to deceive or cheat, especially because of being unworldly or credulous.
2. A person who is not very intelligent or able to understand things easily.

Origin:

From simple + -ton.

Examples:

1. The con artist took advantage of the old man's simpleton nature.
2. He was often taken for a simpleton, but his lack of expression was just his way.
3. Many people considered him a simpleton because of his childlike innocence.
4. The politician's speeches were filled with lies, but the simpletons in the crowd believed every word.
5. The simpleton was easily tricked by the clever scam artist.