naive or naïve (ni-eev, nä-) adj.
Lacking worldly experience and understanding, especially: Simple and guileless; artless: a child with a naive charm. Unsuspecting or credulous
“Students, often bright but naive, betand losesubstantial sums of money on sporting events” (Tim Layden).
Showing or characterized by a lack of sophistication and critical judgment: “this extravagance of metaphors, with its naive bombast” (H.L. Mencken).
Not previously subjected to experiments: testing naive mice.
Not having previously taken or received a particular drug: persons naive to marijuana.
n.
One who is artless, credulous, or uncritical.
In Latin, the word nativus was used to refer to people who lived on farms because to the Roman elite, these simple, unsophisticated people lacked the refinement of those who lived in cities. This concept of naïve arrived in the English language in the 1500s in an earlier form, naif, which is sometimes still used. From the same root comes the word "native".