The term "cell tail" isn't a standard scientific term. In biology, we don't typically refer to a specific structure as a "cell tail."

However, depending on the context, "cell tail" might refer to a few things:

* The trailing edge of a migrating cell: During cell migration, cells often extend a protrusion called a lamellipodium or filopodium at the leading edge. The opposite end of the cell, where the cell body is being pulled along, could be referred to as the "tail."

* The flagellum or cilia of some cells: These are hair-like structures that can help cells move. They are located at the posterior end of the cell and could be considered the "tail" in a loose sense.

* The "tail" of a sperm cell: This is actually called the flagellum, a long, whip-like structure that propels the sperm cell forward.

To understand the specific meaning of "cell tail," you would need more context about where you encountered the term.

Please provide more information about where you heard this term, and I can give you a more precise answer!