from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Of or being a style of painting produced out of doors in natural light.
- adj. Taking place outdoors: plein air dining.
from The Century Dictionary and Cyclopedia
- n. In painting, open air, from the phrase en plein air, in the open air, out of doors: a term used to characterize the modern point of view in painting, which considers the natural effects of light in nature rather than the artificial effects of the studio.
From French (en) plein air, (in) the open air : en, in + plein, full + air, air.(American Heritage® Dictionary of the English Language, Fourth Edition)