Old World bird having a very long tail that jerks up and down as it walks
wagtail详细解释
wag.tail
n.(名词) Any of various chiefly Old World birds of the family Motacillidae, having a slender body with a long tail that constantly wags. 鹡鸰,亟灶巢鸟:主要在西半球的一种鹡鸰科鸟,具有瘦长的身体和不断摆动的尾巴