Wordnet 3.0
ADJECTIVE (1)
1. 
 completely enveloping; 
- Example: "the ambient air"- Example: "ambient sound"- Example: "the ambient temperature"
The Collaborative International Dictionary of English v.0.48:
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.
   [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Ambient \Am"bi*ent\, n.
   Something that surrounds or invests; as, air . . . being a
   perpetual ambient. --Sir H. Wotton.
   [1913 Webster]
WordNet (r) 3.0 (2006):
ambient
    adj 1: completely enveloping; "the ambient air"; "ambient
           sound"; "the ambient temperature"
Moby Thesaurus II by Grady Ward, 1.0:
27 Moby Thesaurus words for "ambient":
   ambience, atmosphere, circling, circumambient, circumferential,
   circumflex, circumfluent, circumfluous, circumjacent, climate,
   embracing, encircling, enclosing, encompassing, enfolding,
   enveloping, environing, medium, milieu, mise-en-scene, neighboring,
   peripheral, roundabout, suburban, surrounding, surroundings,
   wrapping