[pleyn-air; French ple-ner]
pertaining to a manner or style of painting developed chiefly in France in the mid-19th century, characterized by the representation of the luminous effects of natural light and atmosphere as contrasted with the artificial light and absence of the sense of air or atmosphere associated with paintings produced in the studio.
designating a painting executed out of doors and representing a direct response to the scene or subject in front of the artist.
(of a painting) having the qualities of air and natural light.
Origin of plein-air
First recorded in 1890–95; adj. use of plein air
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
of or in the manner of various French 19th-century schools of painting, esp impressionism, concerned with the observation of light and atmosphere effects outdoors
Word Origin for plein-air
C19: from French phrase en plein air in the open (literally: full) air
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
1894, from French phrase en plein air, literally "in the open air." The style developed among French impressionists c.1870.
Online Etymology Dictionary, © 2010 Douglas Harper