Other forms: naturalistically
Something that's naturalistic looks real. If you say "excuse me" to a naturalistic mannequin in a store, then that mannequin must look like the real deal!
Naturalistic things resemble or are influence by reality, so a naturalistic conversation in a movie sounds like something people would really say to each other, and the naturalistic mooing sound your little cousin makes sounds like a real cow. The 1849 definition of naturalistic was "aiming for realism," from natural and its Latin root, naturalis, "according to nature."