Definition
In law, *single* functions as a modifier rather than a standalone term. It carries three recurring legal senses depending on context:
1. **Unitary or individual.** A single instrument, obligation, or condition is one that stands alone — undivided, uncompounded, and affecting only one subject or party. A *single bond*, for instance, is an unconditional bond for payment of a specified sum, as distinguished from a bond with conditions or a joint bond with multiple obligors.
2. **Unmarried.** In family law, tax law, and certain civil statutes, *single* describes a person who is not currently married — whether never married, divorced, or widowed (though widowed status is separately recognized in some legal contexts). This meaning governs filing status categories, eligibility for certain benefits, and adoption qualifications in many jurisdictions.
3. **Sole or exclusive.** In procedural and pleading contexts, *single* can signal that only one instance of a thing is present or permitted — a single entry, a single demise, a single act of adultery — often relevant to whether a remedy applies or a charge is properly pleaded.
Because *single* does no independent legal work without a noun following it, its meaning is entirely context-dependent. Researchers should always read it as a modifier and follow the cross-reference to the compound term.
Common Language
**Modern common usage (Wiktionary):** Wiktionary's primary legal-relevant sense tracks the ordinary meaning: one alone, not coupled or combined; also, unmarried.
**Historical common usage (Webster's 1913):** "One only, as distinguished from more than one; consisting of one alone; individual; separate." Webster's explicitly lists the unmarried sense: "Grows, lives, and dies in single blessedness."
The common and legal meanings are closely aligned in most uses, but a gap emerges in legal instruments. In ordinary speech, *single* simply means one of something. In legal drafting, *single* is often a term of art signaling that an instrument is unconditional and entire — not a descriptor of quantity but a characterization of legal structure. A *single bond* is not merely one bond; it is a bond of a specific legal type defined by the absence of conditions.
Common Confusion
*Single* is frequently used interchangeably with *sole*, *individual*, and *unitary* in legal writing, but precision matters. *Sole* often carries a sense of exclusivity (sole heir, sole proprietor) that *single* does not necessarily imply. *Individual* emphasizes the separateness of a person rather than the undivided character of an instrument. Researchers encountering *single* in older pleading or instrument drafting should resist substituting synonyms without confirming the operative sense in context.
In tax and family law, *single* filing status is a defined statutory category — not simply the absence of marriage. A surviving spouse or head of household may be unmarried but does not file as *single* under federal tax law. The term in that context is narrower than its everyday meaning suggests.
Why It Matters in Research
**Compound terms are the real research targets.** Neither Black's nor Anderson's defines *single* in isolation in any substantive way — both immediately direct the reader to compound entries (single bond, single bill, single entry, single adultery, single demise, single combat, single original). Researchers should treat encounters with *single* as a prompt to look up the full compound term, not the modifier alone.
**Historical sources use *single* to distinguish instrument types.** In older common law and equity contexts, *single* attached to bonds, bills, and entries marks a specific structural type. A *single bond* (also called a *simple bond* or *bill obligatory*) differs meaningfully from a penal bond or a joint bond. This usage is largely archaic in modern practice but appears frequently in 18th- and 19th-century document collections and case law.
**Tax and family law have formalized the unmarried sense.** Modern statutory schemes — particularly federal tax law and state adoption statutes — have given *single* a precise definitional home. Researchers working in these areas should consult the applicable statutory definition rather than relying on common usage, because adjacent statuses (head of household, qualifying widow/widower) may absorb people who are colloquially *single*.
**Jurisdictional variation in adoption contexts.** Whether a *single* person may adopt independently, and what procedural requirements apply, varies considerably by state. Some states explicitly authorize single-parent adoption by statute; others impose additional scrutiny. The encyclopedia entries at family_132 address this directly.
Historical Dictionary Support
Black's 2nd Edition treats *single* as a pure modifier with no independent substantive definition, immediately cross-referencing compound terms: single adultery, single bill, single bond, single combat, single demise, single entry, single original. This approach confirms that *single* had no freestanding legal meaning in classical common law — it was always attached to a noun that carried the doctrinal weight.
Anderson's Dictionary of Law follows the same pattern, directing readers to acknowledgment, adultery, bill, bond, man, original, and sale. The reference to *man* is notable: Anderson's apparently addressed *single man* as a discrete legal category relevant to capacity, contract-making, and possibly military or civil status — a usage that has largely disappeared from modern law but that researchers in 19th-century American legal sources will encounter.
Neither historical source addresses the tax filing sense, which is a 20th-century statutory development. This is a significant gap: researchers using only historical dictionaries will miss the most practically common modern legal use of the term.
Jurisdictional Note
Federal tax law defines *single* filing status by statute and regulation, and the definition does not map perfectly onto state-law marital status. A person legally separated under state law may or may not qualify as *single* for federal tax purposes depending on the applicable tax year rules. State adoption statutes vary widely in their treatment of single applicants.
Encyclopedia Cross-Reference
tax_77: Filing Status Single (The Law Mind Tax Encyclopedia)
family_132: Adoption — Adoption by Same-Sex Couples and Single Parents (The Law Mind Family Law Encyclopedia)
family_194: Tax Implications — Filing Status (Married, Single, Head of Household) (The Law Mind Family Law Encyclopedia)