plein air or plein-air 
(plān′âr, plĕ-nĕr)
(plān′âr, plĕ-nĕr)adj.
1. Of or being a style of painting produced out of doors in natural light.
2. Taking place outdoors: plein air dining.
[From French (en) plein air, (in) the open air : en, in + plein, full + air, air.]