Preternatural \pree-tuhr-NACH-uhr-uhl; -NACH-ruhl\ (adjective) - 1 : Existing outside of nature; differing from the natural; nonnatural. 2 : Surpassing the usual or normal; extraordinary; abnormal. 3 : Beyond or outside ordinary experience; inexplicable by ordinary means.
"She could not get that sound out of her ears even in Mrs. Kingswards sickroom, where the quiet was preternatural, and everybody spoke in the lowest tone, and every step was hushed." -- Margaret Oliphant, 'The Sorceress'
Preternatural derives from the Latin phrase praeter naturam, "beyond nature."