1 If the invitation says black tie, women should wear a floor-length, evening gown. 2  A tuxedo is mandatory if you're a man. 3  This is your chance to dress as if you were headed to the Oscars. 4  Black tie optional means that wearing a tuxedo or long evening gown is not mandatory, but guests should feel free to do so.
Ether is an organic functional group consisting of a disubstituted oxygen, or an oxygen atom bonded to 2 carbon atoms (if adjacent to a ketone, functional group is then called an ester).
Definition of ethereal. 1  1a : of or relating to the regions beyond the earthb : celestial, heavenlyc : unworldly, spiritual. 2  2a : lacking material substance : immaterial, intangibleb : marked by unusual delicacy or refinement this smallest, most ethereal, and daintiest of birds â William Beebec : suggesting the heavens or heaven.