Complex sentence: The surgical definition of "plastic" first appeared in 1839, preceding the modern "engineering material made from petroleum" sense of plastic (coined by Leo Baekeland in 1909) by seventy years.
Split into simpler sentences: The surgical definition of "plastic" first appeared in 1839. It predates the modern "engineering material made from petroleum" sense of plastic (coined by Leo Baekeland in 1909) by seventy years.