fideicommissary substitution

noun

1. : the substitution under Roman and civil law of another heir or donee by a fideicommissum or direction that the original heir or donee at his death or upon some state event or condition transfer the inheritance or gift or a part thereof to the substituted heir or donee

2. : a gift of property under Roman and civil law by will or gift inter vivos wherein the donee (as an heir of the testator or an heir of such person) is directed and under a duty to transfer the property to another or other persons designated as donees