Definition
The condition or state of being the only begotten child of a parent. In legal contexts, unigeniture arises primarily in succession law, inheritance disputes, and ecclesiastical or theological contexts where proof of sole descent from a common ancestor is at issue. The term does not describe a legal rule itself but rather a status — that of being the singular offspring — which may carry legal consequences depending on the applicable scheme of inheritance or entail.
Common Language
Modern common usage (Wiktionary): The state of being the sole begotten.
Historical common usage (Webster's 1913): The state of being the only begotten. [Rare.]
Both Webster's and Wiktionary flag this as rare or archaic in ordinary English, and the legal dictionaries offer no richer definition than the common one. The gap here is not one of meaning but of application: in ordinary English the term is simply descriptive, while in legal usage it becomes evidentiary — a status that may need to be proved or disproved in proceedings touching inheritance, entail, legitimacy, or clerical succession.
Common Confusion
UNIGENITURE vs. PRIMOGENITURE: These terms are sometimes conflated because both relate to a child's status in relation to siblings or potential siblings. Primogeniture is a rule of law or custom giving the eldest child — typically the eldest son in the traditional common law form — priority in succession. Unigeniture is a factual condition: there is only one child. The legal consequences can overlap (an only child is necessarily also the firstborn), but the concepts are distinct. In an entail or inheritance dispute, proving unigeniture eliminates the competition entirely, while primogeniture merely ranks among competitors. Historical sources occasionally use "only begotten" in contexts where they mean "firstborn," and researchers should read surrounding text carefully.
Why It Matters in Research
This term is a navigational challenge precisely because it is so rare. Researchers will almost never encounter it in modern legal materials; its natural habitat is older English and ecclesiastical law texts, early chancery proceedings, and treatises on descent and entail from the eighteenth and nineteenth centuries. Three research traps merit attention.
First, the term should not be confused with primogeniture, the rule giving priority to the firstborn. Unigeniture describes a factual condition — sole offspring status — while primogeniture describes a legal rule of priority among multiple offspring. A testator's will or a court's findings may turn on distinguishing the two: a child may be the firstborn without being the only-born, and vice versa.
Second, in the Law Mind corpus, this term is most likely to appear in ecclesiastical or theological legal materials rather than in common law treatises on real property. The Webster's 1913 citation to Bishop Pearson is instructive — Pearson's Exposition of the Creed is a seventeenth-century theological text, and legal deployments of unigeniture often carry theological freight, particularly in disputes over church offices or benefices where descent or unique sonship had doctrinal significance.
Third, the Black's Law Dictionary (1st Ed.) source text as transmitted is garbled — the entry appears corrupted, running into unrelated material on undue influence. Researchers relying on that edition should treat the unigeniture entry with caution and cross-check against the cleaner second edition and Rapalje & Lawrence.
Historical Dictionary Support
All three historical legal dictionaries offer identical or near-identical definitions: the state of being the only begotten. There is no divergence among them on substance. Rapalje & Lawrence and Black's 2nd Ed. are the more reliable transcriptions; the 1st Ed. entry is textually corrupted in the available source. None of the three dictionaries provides a legal rule, context of application, or citation to authority — they function here purely as vocabulary glosses. This unanimity without elaboration is itself informative: the term carried a clear, stable, and narrow meaning in legal vocabulary, but it was apparently too specialized or rare to warrant extended treatment even in comprehensive legal dictionaries of the period. Researchers should not expect to find doctrinal development within the dictionary tradition and should look instead to primary sources in equity and ecclesiastical courts.