Came across this word in J.M. Robert's Penguin History of the World. Apparently it is the adjectival form of a thaumaturge or thaumaturgy, which in turn is someone who practices magic and/or performs miracles, or that art thereof. The use I found it in was referring to the thaumaturgic aspect of Mid-8th century Frankish history, who believed themselves to have a some what thaumaturgic ethnogenesis. It has a supposed proto-indo-european origin itself.