The Collaborative International Dictionary of English v.0.48:

Electre \E*lec"tre\, Electer \E*lec"ter\, n. [L. electrum: cf.
   F. ['e]lectre mixture of gold and silver. See Electrum.]
   1. Amber. See Electrum. [Obs.]
      [1913 Webster]

   2. A metallic substance compounded of gold and silver; an
      alloy. [Obs.] --Wyclif.
      [1913 Webster]