French term meaning out of doors. Refers to practice of painting entire finished picture out of doors as opposed to simply making preparatory studies or sketches. Pioneered by Constable in Britain c. 1813-17, then from c. 1860 became fundamental to Impressionism. Important technical approach in development of Naturalism. Subsequently became extremely widespread and part of practice of Rural Naturalists for example. Sometimes taken to extremes e.g. By Stanhope Forbes of whom there exists a photograph of him painting on a beach in high wind with canvas and easel secured by guy ropes.