tailtail1 /teɪl/ ●●● noun 1 [countable] the movable part that sticks out at the back of an animal’s body: The dog wagged its tail.2[countable] the back part of an airplane3[countable] the end or back part of something, especially something long and thin: the tail of a comet4tails a)[plural] a man’s jacket with two long parts that hang down the back, worn to formal events b)[uncountable] the side of a coin that does not have a picture of someone’s head on it ANT heads5the tail end of something the last part of an event, situation, or period of time: We watched the tail end of the television program.