Source : Webster's Revised Unabridged Dictionary (1913)

Open-air \O"pen-air`\, a.
   Taking place in the open air; outdoor; as, an open-air game
   or meeting.

Source : WordNet®

open-air
     adj : in the open air; "an alfresco lunch"; "an open-air theater"
           [syn: {alfresco}, {open-air(a)}]