To transfigure is to change or alter something, often so that it becomes even more amazing or beautiful. That colorful mural you painted really transfigures your bedroom!
Transfigure has a Latin root, transfigurare, "change the shape of." While its meaning is similar to transform, there's usually an additional sense of "make better" in transfigure. When you come home dirty and tired after a camping trip, a hot shower and clean clothes will transfigure you. And adding grated cheese, chopped basil, and a drizzle of good olive oil can transfigure a simple dish of pasta.