A letter to the editor written by an environmentalist contains this use of the adjective ethereal:
Contaminated air and water and ethereal space apparently are of no concern [to capitalists].
Here ethereal seems to refer to the physical area above the earth, what I might call “the atmosphere.”
Referring to “ethereal space” in this context is not, strictly speaking, incorrect. The “ethereal realm” is the area above the clouds, but the adjective is closely associated with the supernatural. In general usage, it usually refers to heaven or to creatures or things that are otherworldly:
Several belief systems include ethereal beings such as ghosts, mythological entities, nature spirits, angels, thought-forms, [and] jinns.
Note: Chemists use ethereal with the meaning, “characteristic of, or resembling diethyl ether.” In general usage, however, ethereal is rarely used in a literal sense to describe things in the physical universe.
As an adjective to describe people or objects, ethereal means, “spiritual, non-physical, or abstract in nature; supernatural; incorporeal; nebulous.” It also means, “of a lightness, delicacy, or refinement that does not appear to belong to this world; otherworldly.”
Here are some examples these uses of ethereal:
Fog surrounds a frozen volcano in this ethereal photograph.
The ethereal beauty and benefits of snow
Flowing organza gives this A-line wedding dress an ethereal look.
Gram’s brother used to tease her when she complained. “Oh you’re so frail, so fragile, so ethereal,” he’d say.
Audrey [Hepburn] was meek, gentle and ethereal, understated both in her life and in her work.
Here are some synonyms for ethereal in its various senses: