A person described as "naive" is unsophisticated, simple-minded and often gullible. Though the word is frequently used with a negative connotation, indicating that a person so described is easily tricked or not very bright, it also describes a person who is refreshingly innocent and unaffected.
A person who believes everything he reads or who doesn't have much experience or good judgment is referred to as naive in a way that is less than complimentary. Alternatively, a person who is open and honest in a child-like manner can also be called naive without any intention of insult. The word originates from the Latin "nativus," meaning "not artificial, natural or born."