ethereal

• etherial
• aethereal
• aetherial
• æthereal
• æthereall (obsolete)
• ætherial
• ætheriall (obsolete)

Latin aetherius (“of or pertaining to the ether, the sky, or the air or upper air; ethereal”), from Ancient Greek αἰθέριος (aithérios, “of or pertaining to the upper air; ethereal”).

• (Received Pronunciation) IPA^(key): /ɪˈθɪə.ɹi.əl/
• (US) IPA^(key): /ɪˈθɪɹ.i.əl/, /əˈθɪɹ.i.əl/

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ethereal (comparative more ethereal, superlative most ethereal)

1. Pertaining to the hypothetical upper, purer air, or to the higher regions beyond the earth or beyond the atmosphere; celestial; otherworldly.

   ethereal space

   ethereal regions

   • 1667, John Milton, “Book VII”, in Paradise Lost. A Poem Written in Ten Books, London: Printed [by Samuel Simmons], and are to be sold by Peter Parker […] [a]nd by Robert Boulter […] [a]nd Matthias Walker, […], OCLC 228722708; republished as Paradise Lost in Ten Books: The Text Exactly Reproduced from the First Edition of 1667: […], London: Basil Montagu Pickering […], 1873, OCLC 230729554:

     , lines 1282–4:

     Since to part, / Go heavenly Gueſt, Ethereal Meſſenger, / Sent from whoſe ſovran goodneſs I adore.

   • 1862: Thoreau, Walking.

     I trust that we shall be more imaginative, that our thoughts will be clearer, fresher, and more ethereal, as our sky,...

2. Consisting of ether; hence, exceedingly light or airy; tenuous; spiritlike; characterized by extreme delicacy, as form, manner, thought, etc.
   • 1733–34, Alexander Pope, An Essay on Man, Glasgow: Robert Farie, published 1787, epistle I, lines 237–246, page 7:

     Vaſt chain of being ! which from God began, / Natures ethereal, human, angel, man, / Beaſt, bird, fiſh, inſect ! […]

3. Delicate, light and airy.
4. (chemistry) To do with ether.

• (pertaining to the hypothetical upper, purer air): aereous, mystical, transcendental; See also Thesaurus:cosmic
• (consisting of ether): ethereous; See also Thesaurus:gaseous, Thesaurus:insubstantial, or Thesaurus:subtle
• (delicate, light and airy): gossamer; See also Thesaurus:fragile
• (to do with ether): ethereous, etheric, etherical

• ethereal in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913.