Source : Webster's Revised Unabridged Dictionary (1913)

Harrier \Har"ri*er\, n. [From {Hare}, n.] (Zo["o]l.)
   One of a small breed of hounds, used for hunting hares.
   [Written also {harier}.]

Harrier \Har"ri*er\, n. [From {Harry}.]
   1. One who harries.

   2. (Zo["o]l.) One of several species of hawks or buzzards of
      the genus {Circus} which fly low and harry small animals
      or birds, -- as the European marsh harrier ({Circus
      [ae]runginosus}), and the hen harrier ({C. cyaneus}).

   {Harrier hawk}(?), one of several species of American hawks
      of the genus {Micrastur}.

Source : WordNet®

harrier
     n 1: a persistent attacker; "the harassers were not members of
          the regular army" [syn: {harasser}]
     2: a hound that resembles a foxhound but is smaller; used to
        hunt rabbits
     3: hawks that hunt over meadows and marshes and prey on small
        terrestrial animals