WordWeb Online

1. Characterized by lightness and insubstantiality; as impalpable or intangible as air
   "physical rather than ethereal forms";
   - aeriform, aerial, airy, aery
    
2. (chemistry) of, containing or dissolved in ether
   "ethereal solution"
    
3. Of heaven or the spirit
   "ethereal melodies";
   - celestial, supernal
    
4. Characterized by unusual lightness and delicacy
   "this smallest and most ethereal of birds";
   - gossamer

See also: delicate, heavenly, insubstantial, unreal, unsubstantial

Encyclopedia: Ethereal