Distinct, flexible appendage to the torso of an animal
The tail is the elongated section at the rear (anal) end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolved to lose tail (e.g. frogs and hominid primates), the coccyx is the homologous vestigial of the tail. While tails are primarily considered a feature of vertebrates, some invertebrates such as scorpions and springtails, as well as snails and slugs, have tail-like appendages that are also referred to as tails.
https://en.wikipedia.org/wiki/Tail
The tail is the elongated section at the rear (anal) end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolved to lose tail (e.g. frogs and hominid primates), the coccyx is the homologous vestigial of the tail. While tails are primarily considered a feature of vertebrates, some invertebrates such as scorpions and springtails, as well as snails and slugs, have tail-like appendages that are also referred to as tails.
