This procedure was then labelled the illusionist ceiling painting of the quadratura (di sotto in su). (thetravelmagazine.net)
From the Merriam - Webster's Collegiate Dictionary: Su - pi - ne: Main Entry: 1supine Pronunciation: * s * - * p * n Function: noun Etymology: Middle English supyn, from Late Latin SU PI NUM, from Latin, neu ter of su pi nu s, adjective Date: 15th century (religion.blogs.cnn.com)