資料來源 : Webster's Revised Unabridged Dictionary (1913)

Louis d'or \Lou"is d'or`\ [F., gold louis.]
   Formerly, a gold coin of France nominally worth twenty
   shillings sterling, but of varying value; -- first struck in
   1640.

資料來源 : WordNet®

louis d'or
     n : a former French gold coin