Definition
A single bond is a written obligation — formally a deed — by which the obligor (the party bound) commits himself, his heirs, executors, and administrators to pay a fixed sum of money to the obligee on a specified date. The defining characteristic of a single bond is its unconditional nature: no defeasance clause is attached. The debt stands absolute on its face, with no mechanism for the obligation to be rendered void upon performance of some separate condition.
This distinguishes the single bond sharply from a double bond (also called a penal bond or bond with condition), in which a penalty sum is stated but the bond is made defeasible — capable of being voided — upon the obligor's performance of an underlying obligation, such as repaying a debt, completing an act, or fulfilling a duty. The single bond simply says: pay this sum on this date, period.
The Latin counterpart cited in historical sources is simplex obligatio — a simple or plain obligation.
Common Language
Modern common usage (Wiktionary): In chemistry and general scientific use, a "single bond" is a covalent bond in which one pair of electrons is shared between two atoms, as distinguished from a double or triple bond.
Historical common usage (Webster's 1913): Webster's 1913 does not appear to record "single bond" as a common-language term outside legal usage.
The scientific meaning and the legal meaning share nothing beyond the word "single" as a modifier. A researcher encountering "single bond" in a legal instrument or historical pleading should not import any chemical or structural analogy; the term is purely a classification within the law of obligations and sealed instruments.
Common Confusion
Single bond vs. double bond (penal bond): The most persistent source of confusion is treating these two instruments as variations on a theme when they operate fundamentally differently. A double bond creates a penalty — often double the underlying debt — but contains a defeasance clause that extinguishes the obligation if the condition is performed. A single bond has no such escape valve; the obligation matures on the named date without qualification. Historical court records, pleading books, and conveyancing precedents frequently use both terms, and misreading one for the other can fundamentally alter the researcher's understanding of what a party was legally bound to do.
Single bond vs. promissory note: In modern practice, the simple obligation to pay a fixed sum on a date is almost universally accomplished by a promissory note or negotiable instrument rather than a sealed bond. Researchers working in pre-twentieth-century sources should not assume that "bond" in this context carries the negotiable-instrument attributes of modern notes.
Why It Matters in Research
The single bond is largely a historical instrument. Researchers working in colonial American records, English common law materials, early state court files, and nineteenth-century conveyancing practice will encounter it regularly; researchers in purely modern sources will almost never see the term used in its technical sense.
Several navigational points are worth flagging:
First, the instrument's unconditional character matters for pleading. Because no condition of defeasance existed, a creditor suing on a single bond did not need to allege or prove breach of an underlying condition — the day of payment passed, the sum was due, full stop. Pleading forms for actions on single bonds differ from those on penal bonds, and older practice manuals track this distinction carefully.
Second, the merger of the bond form into statutory debt instruments means that modern "bond" law — covering municipal bonds, bail bonds, performance bonds, and surety bonds — descends primarily from the double bond tradition, not the single bond. When modern encyclopedias and treatises discuss bonds, they are almost never discussing the single bond. This creates a research gap: looking up "bond" in a modern source will not illuminate the single bond's historical operation.
Third, the instrument was executed as a deed, meaning it required sealing under the formal common law rules governing specialty contracts. Statutes of limitation for specialties differed from those for simple contracts, and this distinction governed when actions on single bonds could still be brought. Researchers tracing debt collection in historical court records should verify the applicable limitations period for sealed instruments in the relevant jurisdiction and period.
Fourth, the Latin phrase simplex obligatio appears in Roman law sources and Civilian-influenced materials. Researchers working across common law and civil law traditions, or in mixed jurisdictions, may encounter the Latin form where the English term does not appear.
Historical Dictionary Support
The three historical dictionaries are in substantial agreement on the core definition, and the convergence is notable given how sparse the treatment is. Black's, Bouvier's, and Burrill's all define the single bond as an unconditional obligation to pay a sum certain on a named date, binding the obligor's heirs, executors, and administrators.
Burrill adds the most analytically useful gloss by supplying the Latin equivalent (simplex obligatio) and citing Blackstone's Commentaries (2 Bl. Com. 340), grounding the definition in the classical common law tradition. Blackstone's treatment at that location distinguishes simple bonds from conditional bonds, which is the same double/single distinction described above.
What the historical dictionaries do not address: they say nothing about the procedural consequences of the instrument's unconditional nature, nothing about the seal requirement and its limitation period implications, and nothing about the instrument's practical decline. A researcher relying solely on these dictionary entries will have the definition but will need to consult practice manuals and pleading treatises to understand how the single bond actually functioned in litigation.
Encyclopedia Cross-Reference
The Law Mind Contracts & Commercial Law Encyclopedia: Suretyship — Performance Bonds and Payment Bonds (Construction Context) [contracts_168] — useful for understanding the modern bond tradition that diverged from the historical single bond form.
The Law Mind Immigration Law Encyclopedia: Bond Hearings — Danger and Flight Risk, Bond Amounts, and Redetermination [immigration_82] — illustrates how the word "bond" operates in a modern administrative context entirely distinct from the single bond instrument.