wagtailEnglishOxford New American Dictionarywagtail /ˈwaɡˌtāl, ˈwæɡˌteɪl / ▸ 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.