Source : Webster's Revised Unabridged Dictionary (1913)

Immortelle \Im`mor*telle"\, n.; pl. {Immortelles}. [F. See
   {Immortal}.] (Bot.)
   A plant with a conspicuous, dry, unwithering involucre, as
   the species of {Antennaria}, {Helichrysum}, {Gomphrena}, etc.
   See {Everlasting}.

Source : WordNet®

immortelle
     n : mostly widely cultivated species of everlasting flowers
         having usually purple flowers; southern Europe to Iran;
         naturalized elsewhere [syn: {Xeranthemum annuum}]