Fee tail describes an estate of inheritance in real property which cannot be sold, devised by will, or otherwise alienated by the owner, but which passes by operation of law to the owner's heirs upon his death.

A fee tail was created by words of grant in the deed: "to A and the heirs of his body." The crucial difference between the words of conveyance and the words that created a fee simple, "to A and his heirs," is that the heirs "in tail" must be the children begotten by the landowner. It was also possible to have "fee tail male," which only sons could inherit, and "fee tail female," which only daughters could inherit; and "fee tail special," which had a further condition of inheritance, usually restricting succession to certain "heirs of the body" and excluding others. Land subject to these conditions was said to be entailed or in tail. The restrictions themselves were entailments.

Many jurisdictions have abolished the fee tail estate since it restricts the ready alienation, or transfer, of property. Such states have transformed it into a fee simple through statute.