Preternatural, a.
Etymology: [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.
Shades of meaning
Fernald has no entry of its own for preternatural; he lists it under supernatural.
Where he writes about it:
The supernatural (super, above) is above or superior to the recognized powers of nature; the preternatural (preter, beyond) is aside from or beyond the recognized results or operations of natural law, often in the sense of inauspicious; as, a preternatural gloom. — from supernatural