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}.