She must have been a veritable girl of the late eighties and the early nineties, the naive and idyllic age of Howells, when young men were pure, when they played croquet and sang Swanee River; a girl who sat on a front porch enchanted by the sweetness of lilacs, and hoped that when Almus and she were married they would have a nickel-plated baseburner stove and a son who would become a missionary or a millionaire.
But Martin was at once a scholar who made osmotic pressure determinations almost interesting, a taut swift man whom she could fancy running or making love, and a lonely youngster who naively believed that here in her soft security she was still the girl who had sat with him by the lagoon, still the courageous woman who had come to him in a drunken room at Blackwater.
There are no more uses of "naive" in the book.
Show samples from other sources
You—Aunty, do you know the stuff in that thing makes Dr. Goebbels look like a naive little country boy?
Harper Lee -- Go Set a Watchman
I realize that some naive sliver of me hoped that he was better than this.