Source : Webster's Revised Unabridged Dictionary (1913)

Pellitory \Pel"li*to*ry\, n. [Sp. pelitre, fr. L. pyrethrum. See
   {Bertram}.] (Bot.)
   (a) A composite plant ({Anacyclus Pyrethrum}) of the
       Mediterranean region, having finely divided leaves and
       whitish flowers. The root is the officinal pellitory, and
       is used as an irritant and sialogogue. Called also
       {bertram}, and {pellitory of Spain}.
   (b) The feverfew ({Chrysanthemum Parthenium}); -- so called
       because it resembles the above.

Source : WordNet®

Anacyclus pyrethrum
     n : small Mediterranean plant containing a volatile oil once
         used to relieve toothache [syn: {pellitory}, {pellitory-of-Spain}]