Something unusual that is not magical or supernatural.
It was preternatural to find turtles on my car.
a. [Pref. preter + natural.] Beyond of different from what is natural, or according to the regular course of things, but not clearly supernatural or miraculous; strange; inexplicable; extraordinary; uncommon; irregular; abnormal; as a preternatural appearance; a preternatural stillness; a preternatural presentation (in childbirth) or labor. “This vile and preternatural temper of mind.” South. Syn. — See Supernatural