Source : Webster's Revised Unabridged Dictionary (1913)

Wagtail \Wag"tail`\, n. (Zo["o]l.)
   Any one of many species of Old World singing birds belonging
   to {Motacilla} and several allied genera of the family
   {Motacillid[ae]}. They have the habit of constantly jerking
   their long tails up and down, whence the name.

   {Field wagtail}, any one of several species of wagtails of
      the genus {Budytes} having the tail shorter, the legs
      longer, and the hind claw longer and straighter, than do
      the water wagtails. Most of the species are yellow
      beneath. Called also {yellow wagtail}.

   {Garden wagtail}, the Indian black-breasted wagtail
      ({Nemoricola Indica}).

   {Pied wagtail}, the common European water wagtail ({Motacilla
      lugubris}). It is variegated with black and white. The
      name is applied also to other allied species having
      similar colors. Called also {pied dishwasher}.

   {Wagtail flycatcher}, a true flycatcher ({Sauloprocta
      motacilloides}) common in Southern Australia, where it is
      very tame, and frequents stock yards and gardens and often
      builds its nest about houses; -- called also {black
      fantail}.

   {Water wagtail}.
   (a) Any one of several species of wagtails of the restricted
       genus {Motacilla}. They live chiefly on the shores of
       ponds and streams.
   (b) The American water thrush. See {Water thrush}.

   {Wood wagtail}, an Asiatic wagtail; ({Calobates sulphurea})
      having a slender bill and short legs.