Definition
In law, "sole" means single, alone, or individual — as opposed to joint, aggregate, or married. The term is primarily a modifier that qualifies nouns across several distinct legal contexts rather than a standalone legal concept.
1. Sole (as opposed to joint): Describes ownership, liability, or authority held by one person rather than shared among multiple parties. A sole tenant holds an interest independently; a sole executor administers an estate without a co-executor.
2. Sole (as opposed to aggregate): Describes a legal entity composed of a single natural person rather than a group. A corporation sole — the classic example being a bishop or other officeholder — is a legal entity vested in one person and their successors in office.
3. Sole (as opposed to married): In older law, synonymous with unmarried. Used most prominently in the phrase feme sole, a single woman (whether never married, widowed, or divorced) who holds independent legal capacity. Contrasts with feme covert, a married woman whose legal identity was historically subsumed by her husband's.
4. Sole custody: In modern family law, sole custody describes an arrangement in which one parent holds primary or exclusive parental rights and responsibilities — either physical, legal, or both — without meaningful sharing with the other parent.
---
Common Language
Modern common usage (Wiktionary): The word "sole" in ordinary English most commonly means the underside of a foot or shoe, or refers to a type of flatfish. As an adjective, it means "only" or "exclusive" (e.g., "the sole reason").
Historical common usage (Webster's 1913): Webster's 1913 gives primary attention to the flatfish meaning and related senses, with the adjective sense (only, single, alone) treated as a secondary entry.
The legal use of "sole" as a modifier is essentially continuous with the ordinary adjective meaning — "only" or "single" — but in legal contexts it operates as a term of art that triggers specific doctrines. "Sole" in a deed, will, corporate charter, or custody order carries structural legal consequences that the ordinary adjective does not. A researcher who treats "sole" as merely emphatic, rather than as a definitional signal, may miss legally operative distinctions.
---
Common Confusion
Sole vs. Exclusive: These terms overlap but are not always interchangeable. "Sole" often describes the number of persons holding a right; "exclusive" describes the nature of the right itself — whether others are barred from it. In custody law, "sole legal custody" and "exclusive legal custody" are often used synonymously, but some jurisdictions distinguish them.
Sole vs. Separate: In property law, particularly in the context of married women's property, "sole and separate" was a phrase used to describe property held free from a husband's control. "Sole" here emphasized singularity of ownership, while "separate" emphasized independence from marital claims. The two words reinforced each other and should not be read as redundant when encountered in historical instruments.
---
Recognized Forms
/SUBTYPES
Corporation sole: A legal entity consisting of one person and their successors in an official capacity. Historically associated with ecclesiastical offices; survives in some jurisdictions for public officeholders.
Feme sole: An unmarried woman with full legal capacity to contract, hold property, and sue in her own name. Historically significant because married women lacked this capacity under coverture.
Sole custody: Modern family law usage. May be subdivided into sole physical custody (the child lives primarily with one parent) and sole legal custody (one parent holds decision-making authority over the child's welfare).
Sole trader / sole proprietor: A person conducting business alone, without partners or incorporation. Carries unlimited personal liability.
---
Why It Matters in Research
The word "sole" does real legal work, but its work shifts depending on era and context. Researchers must read it carefully rather than treating it as merely emphatic.
In historical documents — deeds, wills, marriage settlements — "sole" frequently signals the operative legal structure of a transaction. Anderson notes that in wills, "sole" has no fixed technical meaning that defeats contextual interpretation, which means courts construed it flexibly. A researcher analyzing a disputed will or settlement from the 18th or 19th century should not assume "sole" resolved the legal question; it may have been the starting point for litigation.
In coverture-era materials, the feme sole / feme covert distinction is essential to understanding women's legal capacity. Sources before married women's property acts (roughly mid-19th century onward in most common-law jurisdictions) will use "sole" to mark whether a woman could act legally at all. This affects contracts, property transfers, and litigation records. Once married women's property legislation passed, the feme covert category collapsed in practical significance, but historical records and older treatises will still organize analysis around it.
In corporation law, corporation sole appears in older ecclesiastical and public law materials but is rarely encountered in modern commercial research. Researchers working in church law, Crown property, or early American public office succession may need to engage with the doctrine.
In modern family law, "sole custody" is a high-stakes phrase. Many jurisdictions have moved away from the term in favor of "primary" or "residential" custody to reduce adversarial framing, so researchers should check whether a jurisdiction's statutes still use "sole" or have replaced it with functional equivalents. Corpus searches on custody materials should be run against both the old and new terminology.
---
Historical Dictionary Support
The major historical dictionaries agree on the core of the definition: sole means single, alone, or individual, in contrast to joint, aggregate, or married. Black's (both editions), Bouvier, Burrill, and Anderson all converge on this three-part contrast structure — sole/joint, sole/aggregate, sole/married — which reflects the actual doctrinal contexts where the term did work.
Bouvier's is the most precise, tying each contrast to a specific application: sole tenant, feme sole, corporation sole. Burrill briefly notes the Latin root (solus) and cross-references rather than elaborating. Anderson adds the most practically useful nuance by noting that in wills, "sole" carries no fixed technical meaning — a point Black's does not make and one that matters for document interpretation.
Rapalje & Lawrence's entry for this headword appears to have suffered a scanning or compilation error in the available source material; the text presented does not correspond to the term "sole" and instead describes a joint stock company liability concept. Researchers relying on Rapalje & Lawrence for this term should consult the print edition directly.
None of the historical dictionaries address modern custody usage, which developed substantially in the 20th century. Their silence on that application is expected, not a gap in their coverage of the term as it existed in their era.
---
Jurisdictional Note
In family law, some U.S. states have replaced "sole custody" in their statutes with terms like "primary residential parent" or "decision-making responsibility," while others retain "sole custody" as the operative term. The underlying concept is consistent, but corpus searches and statutory interpretation must account for this terminological divergence. Commonwealth jurisdictions similarly vary in their current vocabulary, though older case law across common-law systems will use "sole custody" freely.
---
Encyclopedia Cross-Reference
Child Custody — Joint Custody vs. Sole Custody (The Law Mind Family Law Encyclopedia)
---