The definition of naive is being immature, unaware or overly trusting.(adjective)
An example of naive is someone who believes that the moon is made of cheese because their mother said it was.
See naive in Webster's New World College Dictionary
Origin: Fr, fem. of naïf < L nativus, natural, native
See naive in American Heritage Dictionary 4
Origin: French naïve
Origin: , feminine of naïf
Origin: , from Old French naif, natural, native
Origin: , from Latin nātīvus, native, rustic
Origin: , from nātus
Origin: , past participle of nāscī, to be born; see genə- in Indo-European roots.
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