reversion

Reversion is the act or process of returning to a previous state, condition, or owner. In law, a reversion is a future interest retained by a grantor when property is conveyed for a limited duration, such as a life estate. When the possessory estate ends, ownership reverts to the grantor or the grantor’s heirs. This is distinct from a remainder, which is a future interest assigned to a third party.

In biology and genetics, a genetic reversion (reversion mutation) restores the original phenotype or genotype after a prior mutation. True revertants arise from a correcting second mutation at the same site; second-site revertants restore function via alternative changes. Reversion can also describe a tendency for populations to revert toward ancestral traits under selection or drift.

In statistics and finance, reversion often refers to mean reversion—the tendency of a variable to move toward its historical average over time. This concept underpins certain risk models and investment strategies.

In computing, to revert is to undo changes and restore a previous version of a document or program. Version control systems provide revert or rollback operations to restore earlier commits or file states.

In other contexts, reversion may describe a shift back to older cultural, behavioral, or evolutionary states, or the restoration of a trait in breeding studies.