wagtail Syllabification: (wag·tail)Pronunciation: /ˈwagˌtāl/Definition of wagtail noun a slender Eurasian and African songbird with a long tail that is frequently wagged up and down, typically living by water. Family Motacillidae: two genera, in particular Motacilla, and several species wagtail in other Oxford dictionaries Definition of wagtail in the British & World English dictionary