Reversion

The act of returning, or coming back; return.

That which reverts or returns; residue.

The returning of an esttate to the grantor or his heirs, by operation of law, after the grant has terminated; hence, the residue of an estate left in the proprietor or owner thereof, to take effect in possession, by operation of law, after the termination of a limited or less estate carved out of it and conveyed by him.

Hence, a right to future possession or enjoiment; succession.

A payment which is not to be received, or a benefit which does not begin, until the happening of some event, as the death of a living person.

A return towards some ancestral type or character; atavism.

(genetics) a return to a normal phenotype (usually resulting from a second mutation)

(law) an interest in an estate that reverts to the grantor (or their heirs) at the end of some period (e.g., the death of the grantee)

returning to a former state