Source : Webster's Revised Unabridged Dictionary (1913)

Ambient \Am"bi*ent\, a. [L. ambiens, p. pr. of ambire to go
   around; amb- + ire to go.]
   Encompassing on all sides; circumfused; investing. ``Ambient
   air.'' --Milton. ``Ambient clouds.'' --Pope.

Ambient \Am"bi*ent\, n.
   Something that surrounds or invests; as, air . . . being a
   perpetual ambient. --Sir H. Wotton.

Source : WordNet®

ambient
     adj : completely enveloping; "the ambient air"; "ambient sound";
           "the ambient temperature"