1. en plein air - Adjective
2. en plein air - Adverb
en plein air (not comparable)
(painting) in the open air, alfresco, outside, outdoors
American impressionists too, such as those of the Old Lyme school, were avid painters en plein air. Source: Internet
Boudin taught Monet " en plein air " (outdoor) techniques for painting. Source: Internet
In Canada, the Group of Seven and Tom Thomson are examples of en plein air advocates. Source: Internet
The Newlyn School in England is considered another major proponent of the technique in the latter 19th century. citation The popularity of painting en plein air increased in the 1840s with the introduction of paints in tubes (like for toothpaste ). Source: Internet