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).
In the scientific context it refers what we once believed to be a sort of membrane that covered particular elements or particles such as light or a medium in which these particles move about and exist in. In the theological or philosophical sense the ether refers to the essence of the universe. Sort of like the pool of energy from which the universe came from or is feed from. It may also refer to the source of magic, a cure all medicine, the birth place of magical beings such as dragons or fairies.