alfresco(s = adj.all) open-air - in the open air; "an alfresco lunch"; "an open-air theater"

   alfresco(r = adv.all) out of doors, outdoors, outside - outside a building; "in summer we play outside"

   In the open-air. Smollett. [1913 Webster]

alfresco, adv. & adj. in the open air (we lunched alfresco; an alfresco lunch).

Etymology:
It. al fresco in the fresh (air)