The word "ethera" is unknown.

ether (as in "inhalation anesthetic") n. : a colorless volatile highly inflammable liquid used as an inhalation anesthetic ether (as in "quintessence") n. : (archaic) the fifth and highest element after air and earth and fire and water; was believed to be the substance composing all heavenly bodies ether (as in "medium") n. : a medium that was once supposed to fill all space and to support the propagation of electromagnetic waves