How to say "ether" in Japanese

• 天空てんくうCommon
  nounHere 'ether' means the upper sky or firmament, a literary sense; the word itself is a common way to say 'sky', and it never refers to the chemical substance.
  この国くにの王おうは人ひとではなく、はるか天空てんくうに居いられるという三さん対たいの翼つばさを持もつ神獣しんじゅうなんだ。↗

  The king of this country isn't a person, but a divine beast with three pairs of wings said to be in far away in the sky.
• エーテル
  nounThe straightforward loanword for the scientific senses: the chemical substance, formerly used as an anesthetic, and the hypothetical medium of space in physics.
• イーサ
  nounA phonetic borrowing of the English pronunciation, found chiefly in technical loan usage; on its own it is seldom the word you want—reach for エーテル for the scientific senses.
• 魔素まそ
  nounCovers 'ether' as it appears in fantasy fiction: magical particles or energy permeating a fictional world, close to 'mana'; not a word for the chemical or the sky.

Choose 「エーテル」 for the scientific senses—the chemical substance or the hypothetical medium of space—天空 for the poetic upper sky, 魔素 for magical energy in fantasy settings, and 「イーサ」 only in technical loan usage.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 天空てんくうsky
• エーテルether
• イーサether
• 魔素まそmagical particles (permeating the world in fantasy)