Ingenuous – innocent and unsuspecting, honest, sincere and trusting
The engine's house (ingenuous) always had the doors and windows left open. It was very trusting of her.
Examples of ingenuous in a sentence
My ingenuous six-year-old sister still believes there is an Easter bunny.
It has to be said it was rather ingenuous of him to ask a complete stranger to take care of his luggage.
Jessica’s ingenuous nature made her an easy target for the con man.