Definition
To cohabit is to live together in the same dwelling with another person in a relationship characterized by domestic intimacy. The term carries two distinct legal registers that have diverged sharply over time:
1. General habitation sense. In older property and settlement law, to cohabit simply meant to reside together under the same roof, without any necessary implication of a sexual or conjugal relationship. Two sisters living in the same house could be said to cohabit.
2. Conjugal or quasi-marital sense. In the context of marriage law, domestic relations, and criminal statutes, to cohabit means to live together as husband and wife — sharing bed, board, and domestic life in a manner that resembles or constitutes a marital household. This is the dominant modern legal sense. It does not require legal marriage; the focus is on the quality and continuity of the domestic arrangement, not its formal status.
In contemporary family law, "cohabitation" most often describes unmarried partners who share a household in an intimate, marriage-like relationship. Courts examining cohabitation in this context look to factors such as shared residence, shared finances, sexual intimacy, public representation as a couple, and duration of the arrangement.
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Common Language
Modern common usage (Wiktionary): To live together with someone else, especially in a romantic and sexual relationship but without being married; also, more loosely, to coexist in the same environment.
Historical common usage (Webster's 1913): To inhabit or reside in company, or in the same place or country; also, to dwell together as husband and wife, with the law presuming such cohabitation to continue even after voluntary separation.
The gap between common and legal meaning is real but subtle. Ordinary English today emphasizes the unmarried aspect — cohabitation as a deliberately non-marital arrangement. Legal sources use the word more flexibly: in criminal statutes (particularly anti-polygamy law), it signals a marriage-like relationship regardless of formality; in settlement and property cases, it can mean mere shared residence with no conjugal implication at all. Researchers should resist importing the modern common meaning (unmarried + romantic) into historical legal sources where the term may carry either a broader or a narrower sense.
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Common Confusion
COHABIT vs. RESIDE/DWELL: In early property law, cohabitation could be synonymous with simple co-residence. In domestic relations and criminal law, it means something more — a conjugal or quasi-marital domestic arrangement. A boarder and a landlord reside together; they do not cohabit in the legal family-law sense.
COHABIT vs. MARRIAGE: Modern statutes and judicial opinions sometimes condition rights or obligations on whether parties "cohabit" rather than whether they are married. These are not synonyms. Cohabitation describes a factual domestic arrangement; marriage is a legal status. The distinction matters acutely in alimony modification disputes, benefits eligibility, and common-law marriage jurisdictions.
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Why It Matters in Research
The word cohabit is a moving target across time, jurisdiction, and doctrinal context. Three research traps warrant attention.
First, contextual instability in historical sources. Older cases and statutes use cohabit to mean simply living under the same roof. If you encounter the term in a 19th-century settlement dispute or a testamentary case, do not assume the conjugal sense. The source material here illustrates this directly: Black's and Burrill's both preserve the neutral residential meaning alongside the conjugal one.
Second, the anti-polygamy statute context. Anderson's entry flags the federal anti-polygamy act of 1882, where cohabitation with more than one woman was itself criminalized — meaning the word bore significant criminal weight independent of any formal marriage ceremony. Cases from this line treat cohabitation as a factual substitute for marriage proof. This usage is now largely historical but resurfaces in research on Mormon legal history, plural marriage prosecutions, and the evolution of marriage regulation.
Third, modern family law bifurcation. Contemporary litigation over property division, palimony, alimony modification, and government benefits frequently turns on whether parties "cohabited." Courts apply multi-factor tests rather than a single bright-line rule, and the factors vary by jurisdiction. Researchers working in this area need to identify which jurisdiction's definition of cohabitation controls, because the same domestic arrangement may qualify in one state and not another.
The term also connects upward to common-law marriage doctrine in jurisdictions that recognize it: prolonged cohabitation combined with holding out as married can be foundational evidence for a common-law marriage claim.
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Historical Dictionary Support
Black's and Burrill's are in substantial agreement, effectively identical in their core formulation: cohabit means to live together as husband and wife, or more neutrally, to live together in the same house. Both preserve the dual-register character of the word, and both cite the same sources (Burrows's Settlement Cases and 2 Vern. 323).
Anderson's adds important doctrinal texture the other dictionaries omit. Anderson distinguishes the general (mere dwelling together) from the criminal-statute sense, signals that cohabitation in the polygamy-statute context required something more than casual visits or occasional contact, and provides case references grounding the definition in real litigation. Anderson's formulation — that cohabitation means to dwell with someone, not merely to visit — anticipates modern courts' multi-factor approach and is worth consulting when working through historical domestic-relations disputes.
What the historical dictionaries do not address: the modern family law setting in which cohabitation between unmarried partners generates independent legal rights and obligations (property claims, support claims, parentage issues). That development postdates all three sources. Researchers should treat the historical entries as providing the foundation for the conjugal-habitation meaning while turning to modern authorities for the rights-and-obligations framework built on that foundation.
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Jurisdictional Note
Significant variation exists in how states define cohabitation for purposes of alimony modification, domestic partnership benefits, and statutory presumptions. Some states require proof of a romantic or sexual component; others look primarily to shared residence and economic interdependence. A small number of states have codified definitions; most leave the question to case-by-case judicial determination. Research in any specific jurisdiction requires consulting that state's domestic relations statutes and controlling appellate authority.
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Encyclopedia Cross-Reference
family_179: Unmarried Cohabitants — Property Rights and Division (The Law Mind Family Law Encyclopedia)
family_181: Unmarried Cohabitants — Palimony and Support Obligations (The Law Mind Family Law Encyclopedia)
family_184: Unmarried Cohabitants — Parentage Rights of Unmarried Partners (The Law Mind Family Law Encyclopedia)
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