Definition
A surname is the family name or last name borne in common by members of a family, as distinguished from a given name (also called a Christian name, forename, or first name). In legal contexts, the surname is the heritable or inherited component of a person's full legal name — the name that identifies family lineage rather than individual identity.
At common law, no person was required to carry a fixed surname by birth, but the surname became the legally operative identifier for purposes of property succession, contract, court proceedings, and official record-keeping. A person's legal name, for most jurisdictional purposes, is understood to consist of a given name and a surname together.
Common Language
Modern common usage (Wiktionary): The portion of a person's name that is generally hereditary or treated as an indicator of family membership, shared with other members of the family or derived from their names; distinguished from given name(s).
Historical common usage (Webster's 1913): A name added to, or over and above, the baptismal or Christian name, which becomes a family name; an appellation added to the original name.
The common and legal meanings here are substantially aligned, but the legal meaning carries weight that ordinary usage does not: in legal instruments, court filings, deeds, and vital records, the surname is the anchoring identifier. Common usage treats the surname as a social convention; legal usage treats it as a term of art that can affect the validity of instruments, the identity of parties, and the chain of title. Historical legal sources also carry a theological register — "Christian name" as the counterpart to surname — that modern researchers must account for when reading older records.
Common Confusion
Surname vs. family name vs. last name: These three phrases are functionally synonymous in modern usage and in most modern legal contexts. Historical legal sources, however, tend to use "surname" as the technical term and "Christian name" as its counterpart. Researchers reading 19th-century instruments or pleadings should note that "family name" and "last name" appear infrequently in those sources; "surname" is the operative term of art throughout that period.
Surname vs. given name vs. middle name: Legal instruments have historically required at minimum a given name and a surname to identify a party. Middle names occupy an uncertain traditional status — they were not always required and sometimes treated as superfluous. Discrepancies involving middle names or initials in instruments and records have generated a distinct body of case law on identity of parties, though middle names are not "surnames" and the two should not be conflated.
Why It Matters in Research
Researchers working in the Law Mind corpus will encounter "surname" primarily in three contexts: the law of names and name changes, the construction of legal instruments (wills, deeds, contracts), and vital records and identity documentation.
In name-change proceedings, the distinction between surname and given name matters procedurally — many jurisdictions have historically treated surname changes differently from given-name changes, particularly for married women and children, and statutory schemes are not uniform.
In the construction of instruments, misspelling, omission, or variation of a surname has been a recurring source of litigation over the identity of parties. Historical courts applied the idem sonans doctrine — two names that sound alike, even if spelled differently, may be legally treated as the same name — most frequently to surnames. Researchers tracing a chain of title or interpreting a legacy must be alert to variant spellings of surnames across documents, which historical dictionaries treat only superficially.
In vital records research and legal history, the surname as a fixed heritable identifier is a relatively modern institution. Medieval and early modern legal records frequently identified individuals by given name plus locative, occupational, or patronymic descriptors that had not yet stabilized into inherited surnames. Researchers working with pre-modern legal materials should not assume that surname conventions apply.
The Bouvier and Black entries note that the etymology of "surname" relates to the practice of writing the family name above the given name in judicial writings and contracts — a useful reminder that the visual conventions of historical instruments may differ from modern practice and should not be misread.
Historical Dictionary Support
Black's Law Dictionary (both editions) and Bouvier's Law Dictionary agree on the core definition: the surname is the family name, the name common to all members of a family, the part of a name not given in baptism. The formulation is consistent across all major shelf sources that address the term directly.
Bouvier adds the etymological note that surnames were originally written over (i.e., above) the given name in judicial writings — "sur" being a French preposition meaning "over" or "upon." This is historically illuminating and helps explain why the term appears in older instruments in ways that may confuse modern researchers.
Anderson's Dictionary of Law simply cross-references to NAME, reflecting how tightly the concept was integrated into the broader law-of-names framework rather than treated as a standalone doctrine.
Rapalje & Lawrence's entry under this headword is a mismatch — the reproduced text addresses suretyship rather than surname, which appears to be an indexing or transcription error in that source. Researchers relying on Rapalje & Lawrence for this term should disregard that entry and consult the other shelf dictionaries.
None of the historical dictionaries address name change, hyphenated surnames, married name conventions at any depth, or the treatment of surnames in non-Western naming traditions — all of which are significant research areas in modern legal practice that require consulting primary statutory and case law sources.
Jurisdictional Note
Surname change on marriage, divorce, and by court petition is governed by state statute in the United States, and rules vary materially on who may petition, what standard applies, and whether name changes are automatic or require court order. In the United Kingdom and Commonwealth jurisdictions, the concept of "surname" is well established but the formal legal infrastructure around name change differs significantly from American practice.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia — Names; Identity and Legal Personhood; Idem Sonans