The Collaborative International Dictionary of English v.0.48:

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.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Feverfew \Fe"ver*few\ (f[=e]"v[~e]r*f[=u]), n. [AS. feferfuge,
   fr. L. febrifugia. See fever, Fugitive, and cf.
   Febrifuge.] (Bot.)
   A perennial plant (Pyrethrum Parthenium, or Chrysanthemum
   Parthenium) allied to camomile, having finely divided leaves
   and white blossoms; -- so named from its supposed febrifugal
   qualities.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Chrysanthemum parthenium
    n 1: bushy aromatic European perennial herb having clusters of
         buttonlike white-rayed flower heads; valued traditionally
         for medicinal uses; sometimes placed in genus Chrysanthemum
         [syn: feverfew, Tanacetum parthenium, Chrysanthemum
         parthenium]