Meaning

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

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

noun a reappearance of an earlier characteristic

originBorrowed into late Middle English from Old French reversion (modern réversion), from Latin reversio, from revertō. By surface analysis, revert + -sion.

Etymology from Wiktionary, CC BY-SA 3.0