As in slang for the posterior, backside, and also the female pudenda, dates from the 14th century. Tail as in the reverse side of a coin dates from the late 1600s. As in a harlot or prostitute, dates from the late 18th century. As in to follow someone, dates from the late 19th century. As in a piece of tail, referring to a woman as a sex object, is American slang that dates from the 1930s.