The Collaborative International Dictionary of English v.0.48:

Pellitory \Pel"li*to*ry\, n. [OE. paritorie, OF. paritoire, F.
   pari['e]taire; (cf. It. & Sp. parietaria), L. parietaria the
   parietary, or pellitory, the wall plant, fr. parietarius
   belonging to the walls, fr. paries, parietis a wall. Cf.
   Parietary.] (Bot.)
   The common name of the several species of the genus
   Parietaria, low, harmless weeds of the Nettle family; --
   also called wall pellitory, and lichwort.
   [1913 Webster]

   Note: Parietaria officinalis is common on old walls in
         Europe; Parietaria pennsylvanica is found in the
         United States; and six or seven more species are found
         near the Mediterranean, or in the Orient.
         [1913 Webster]

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]

WordNet (r) 3.0 (2006):

pellitory
    n 1: herb that grows in crevices having long narrow leaves and
         small pink apetalous flowers [syn: pellitory-of-the-wall,
         wall pellitory, pellitory, Parietaria difussa]
    2: a small Mediterranean plant containing a volatile oil once
       used to relieve toothache [syn: pellitory, pellitory-of-
       Spain, Anacyclus pyrethrum]