The Collaborative International Dictionary of English v.0.48:

Agrimony \Ag"ri*mo*ny\, n. [OE. agremoyne, OF. aigremoine, L.
   agrimonia for argemonia, fr. Gr. ?.] (Bot.)
   (a) A genus of plants of the Rose family.
   (b) The name is also given to various other plants; as, hemp
       agrimony (Eupatorium cannabinum); water agrimony
       (Bidens).
       [1913 Webster]

   Note: The Agrimonia eupatoria, or common agrimony, a
         perennial herb with a spike of yellow flowers, was once
         esteemed as a medical remedy, but is now seldom used.
         [1913 Webster]

WordNet (r) 3.0 (2006):

agrimony
    n 1: a plant of the genus Agrimonia having spikelike clusters of
         small yellow flowers [syn: agrimonia, agrimony]