What is the meaning of the word "wagtail"?

Definitions:

  1. A small bird known for their long tails that they constantly wag or move up and down, mainly found in Europe, Africa and Asia and are commonly seen near water bodies. copy to clipboard NOUN
    • Wagtails are often seen near water bodies, where they can find food and nesting sites. copy to clipboard
  2. A small, slender bird, characterized by their long tails, which they frequently wag up and down, giving them their name. copy to clipboard NOUN
    • The wagtail flitted along the riverbank, wagging its tail as it searched for insects. copy to clipboard