Why is the ninth month called September?
reversion re·ver·sion (rĭ-vûr'zhən)
The return of a trait or characteristic peculiar to a remote ancestor, especially one that has been suppressed for one or more generations.
A return to the normal phenotype, usually by a second mutation.
in Anglo-American law, interest held by a prior owner in property given to another, which, upon the happening of some future event, will return to that prior owner. A reversion is itself specific property, and it can be sold or disposed of as property by the reversion owner. One who holds property subject to a reversion interest held by another is under certain obligations as to the use of that property. Generally, such an owner must reasonably protect the property from spoilage or diminution in value, for the sake of the future owner.