Physics. Of the nature or consisting of the luminiferous ether (cf. ether, n. 3); of or relating to this substance. Now historical.

Something likened to ether (esp. in senses 3 4); the distinctive quality or character that seems to surround or be generated by a person, thing…

= ethereal, adj. (in various senses).

Having the form of ether (ether, n. 3); ethereal.

= ethereal, adj. (in various senses).