The Collaborative International Dictionary of English v.0.48:

Heir \Heir\, v. t.
   To inherit; to succeed to. [R.]
   [1913 Webster]

         One only daughter heired the royal state. --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

            I am my father's heir and only son.   --Shak.
      [1913 Webster]

   2. One who receives any endowment from an ancestor or
      relation; as, the heir of one's reputation or virtues.
      [1913 Webster]

            And I his heir in misery alone.       --Pope.
      [1913 Webster]

   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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

heir
    n 1: a person who is entitled by law or by the terms of a will
         to inherit the estate of another [syn: heir, inheritor,
         heritor]
    2: a person who inherits some title or office [syn: successor,
       heir]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "heir":
   aftermath, apparent heir, backup man, beneficiary,
   beneficiary heir, breed, brood, children, conclusion, consequence,
   coparcener, descendant, descendants, descent, dynasty, effect,
   family, fideicommissary heir, fiduciary heir, fruit, grandchildren,
   great-grandchildren, heir apparent, heir expectant, heir general,
   heir in tail, heir of entail, heir of inventory, heir of line,
   heir portioner, heir presumptive, heir whatsoever, heiress, heirs,
   heritor, hostages to fortune, inheritor, inheritors, inheritress,
   inheritrix, issue, joint heir, kids, legatee, line, lineage,
   little ones, new generation, next in line, offspring, orphan,
   posterity, presumptive heir, progeny, relict, remainderman,
   replacement, reversioner, rising generation, seed, sequel, sons,
   succession, successor, survivor, treasures, widow, widower,
   younglings, youngsters



Easton's 1897 Bible Dictionary:

Heir
   Under the patriarchs the property of a father was divided among
   the sons of his legitimate wives (Gen. 21:10; 24:36; 25:5), the
   eldest son getting a larger portion than the rest. The Mosaic
   law made specific regulations regarding the transmission of real
   property, which are given in detail in Deut. 21:17; Num. 27:8;
   36:6; 27:9-11. Succession to property was a matter of right and
   not of favour. Christ is the "heir of all things" (Heb. 1:2;
   Col. 1:15). Believers are heirs of the "promise," "of
   righteousness," "of the kingdom," "of the world," "of God,"
   "joint heirs" with Christ (Gal 3:29; Heb. 6:17; 11:7; James 2:5;
   Rom. 4:13; 8:17).


Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR. One born in lawful matrimony, who succeeds by descent, and right of
blood, to lands, tenements or hereditaments, being an estate of inheritance.
It is an established rule of law, that God alone can make an heir. Beame's
Glanville, 143; 1 Thomas, Co. Lit. 931; and Butler's note, p. 938. Under the
word heirs are comprehended the heirs of heirs in infinitum. 1 Co. Litt. 7
b, 9 a, 237 b; Wood's Inst. 69. According to many authorities, heir may be
nomen collectivuum, as well in a deed as in a will, and operate in both in
the same manner, as heirs in the plural number. 1 Roll. Abr. 253; Ambl. 453;
Godb. 155; T. Jones, 111; Cro, Eliz. 313; 1 Burr. 38; 10 Vin. Abr. 233, pl.
1; 8 Vin. Abr. 233; sed vide 2 Prest. on, Est. 9, 10. In wills, in order to
effectuate the intention of the testator, the word heirs is sometimes
construed to mean next of kin; 1 Jac. & Walk. 388; and children, Ambl. 273.
See further, as to the force and import of this word, 2 Vent. 311; 1 P. Wms.
229; 3 Bro. P. C. 60, 454; 2 P. Wms. 1, 369; 2 Black. R. 1010; 4 Ves. 26,
766, 794; 2 Atk. 89, 580; 5 East Rep. 533; 5 Burr. 2615; 11 Mod. 189; 8 Vin.
Abr. 317; 1 T. R. 630; Bac. Abr. Estates in fee simple, B.
     2. There are several kinds of heirs specified below.
     3. By the civil law, heirs are divided into testamentary or instituted
heirs legal heirs, or heirs of the blood; to which the Civil Code of
Louisiana has added irregular heirs. They are also divided into
unconditional and beneficiary heirs.
     4. It is proper here to notice a difference in the meaning of the word
heir, as it is understood by the common and by, the civil law. By the civil
law, the term heirs was applied to all persons who were called to the
succession, whether by the act of the party or by operation of law. The
person who was created universal successor by a will, was called the
testamentary heir; and the next of kin by blood was, in cases of intestacy,
called the heir at law, or heir by intestacy. The executor of the common law
is, in many respects, not unlike the testamentary heir of the civil law.
Again, the administrator in many respects corresponds with the heir by
intestacy. By the common law, executors unless expressly authorized by the
will and administrators, have no right, except to the personal estate of the
deceased; whereas, the heir by the civil law was authorized to administer
both the personal and real estate. 1 Brown's Civ. Law, 344; Story, Confl. of
Laws, Sec. 508.
     5. All free persons, even minors, lunatics, persons of insane mind or
the like, may transmit their estates as intestate ab intestato, and inherit
from others. Civ. Code of Lo., 945; Accord, Co. Lit. 8 a.
     6. The child in its mother's womb, is considered as born for all
purposes of its own interest; it takes all successions opened in its favor,
after its conception, provided it be capable of succeeding at the moment of
its birth. Civ. Code of Lo. 948. Nevertheless, if the child conceived is
reputed born, it is only in the hope of its birth; it is necessary then that
the child be born alive, for it cannot be said that those who are born dead
ever inherited. Id. 949. See In ventre sa mere.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, LEGAL, civil law. A legal heir is one who is of the same blood of the
deceased, and who takes the succession by force of law; this is different
from a testamentary or conventional heir, who takes the succession in virtue
of the disposition of man. See Civil, Code of Louis. art. 873, 875; Dict. de
Jurisp., Heritier legitime. There are three classes of legal heirs, to wit;
the children and other lawful descendants; the fathers and mothers and other
lawful ascendants; and the collateral kindred. Civ. Code of Lo. art. 883.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, COLLATERAL. A collateral heir is one who is not of the direct line of
the deceased, but comes from a collateral line; as, a brother, sister, an
uncle and aunt, a nephew, niece, or cousin of the deceased.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, CONVENTIONAL, civil law. A conventional heir is one who takes a
succession by virtue of a contract; for example, a marriage contract, which
entitles the heir to the succession.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, FORCED. Forced heirs are those who cannot be disinherited. This term
is used among the civilians. Vide Forced heirs



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, GENERAL. Heir at common in the English law. The heir at common law is
he who, after his father or ancestor's death has a right to, and is
introduced into all his lands, tenements and hereditaments. He must be of
the whole blood, not a bastard, alien, &c. Bac. Abr. Heir, B 2; Coparceners;
Descent.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, IRREGULAR. In Louisiana, irregular heirs are those who are neither
testamentary nor legal, and who have been established by law to take the
succession. See Civ. Code of Lo. art. 874. When the deceased has left
neither lawful descendants nor ascendants, nor collateral relations, the law
calls to his inheritance either the surviving husband or wife, or his or her
natural children, or the state. Id. art., 911. This is called an irregular
succession.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR. APPARENT. One who has an indefeasible right to the inheritance,
provided he outlive the ancestor. 2 Bl. Com. 208.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, BENEFICIARY. A term used in the civil law. Beneficiary heirs are those
who have accepted the succession under the benefit of an inventory regularly
made. Civ. Code of Lo. art. 879. If the heir apprehend that the succession
will be burdened with debts beyond its value, he accepts with benefit of
inventory, and in that case he is responsible only for the value of the
succession. See inventory, benefit of.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, TESTAMENTARY, civil law. A testamentary heir is one who is constituted
heir by testament executed in the form prescribed by law. He is so called to
distinguish him from the legal heirs, who are called to the succession by
the law; and from conventional heirs, who are so constituted by a contract
inter vivos. See Haeres factus; Devisee.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

HEIR, UNCONDITIONAL. A term used in the civil law, adopted by the Civil Code
of Louisiana. Unconditional heirs are those who inherit without any
reservation, or without making an inventory, whether their acceptance be
express or tacit. Civ. Code of Lo. art. 878.