假定继承人

[ noun ]
a person who expects to inherit but whose right can be defeated by the birth of a nearer relative
<noun.person>

Heir \Heir\ ([^a]r), n. [OE. heir, eir, hair, OF. heir, eir, F.
hoir, L. heres; of uncertain origin. Cf. {Hereditary},
{Heritage}.]
1. One who inherits, or is entitled to succeed to the
possession of, any property after the death of its owner;
one on whom the law bestows the title or property of
another at the death of the latter.

I am my father's heir and only son. --Shak.

2. One who receives any endowment from an ancestor or
relation; as, the heir of one's reputation or virtues.

And I his heir in misery alone. --Pope.

{Heir apparent}. (Law.) See under {Apparent}.

{Heir at law}, one who, after his ancector's death, has a
right to inherit all his intestate estate. --Wharton (Law
Dict.).

{Heir presumptive}, one who, if the ancestor should die
immediately, would be his heir, but whose right to the
inheritance may be defeated by the birth of a nearer
relative, or by some other contingency.