Definition
In legal contexts, "sick" is not a term of art but a descriptive term that appears across multiple bodies of law to characterize a condition of illness, incapacity, or physical impairment. Its legal significance arises not from the word itself but from the statutory or contractual framework in which it appears. Key contexts include:
1. Employment and labor law: "Sick" describes the condition triggering entitlement to sick leave, sick pay, or related benefits under employment contracts, collective bargaining agreements, and statutes governing paid and unpaid leave.
2. Tax law: Payments received on account of being "sick" — including wages, insurance proceeds, and employer-funded sick pay — have specific exclusion and inclusion rules under federal income tax law. Whether a payment is characterized as compensation for sickness affects its taxability.
3. Testamentary and capacity law: A testator described as "sick" in historical documents may bear on questions of testamentary capacity, undue influence, or the circumstances of execution. Courts have distinguished between sickness affecting physical condition and sickness affecting mental capacity.
4. Insurance: "Sick" and "sickness" are operative terms in disability and health insurance policies, often defined specifically within the policy to limit or expand coverage.
Common Language
Modern common usage (Wiktionary): To vomit; to fall sick; to sicken.
Historical common usage (Webster's 1913): Affected with disease of any kind; ill; indisposed; not in health. Also, inclined to vomit; nauseated. Also, having a strong dislike; disgusted; surfeited.
The gap between common and legal meaning is narrow but consequential in specific contexts. In ordinary language, "sick" is a broad, informal term for any degree of unwellness. In legal instruments — particularly insurance policies, employment contracts, and tax statutes — the word carries a more bounded meaning shaped by definition clauses and interpretive case law. A person who is "sick of flattery" (Webster's idiomatic usage) is not sick in any legally operative sense. Conversely, courts and agencies have grappled with whether chronic conditions, pregnancy, mental illness, and substance dependency qualify as "sickness" for purposes of specific legal entitlements.
Common Confusion
"Sick" and "disability" are frequently conflated. Disability, in most legal frameworks, is a defined term of art with durational and functional thresholds that "sick" does not inherently carry. Short-term sickness may not constitute disability under the Americans with Disabilities Act or Social Security definitions, even if it triggers sick leave benefits under an employment contract. Researchers should not assume that sources discussing sickness benefits and sources discussing disability benefits are analyzing the same legal category.
Similarly, "sickness" and "injury" are distinguished in many insurance and tax contexts. The distinction between an illness (arising from internal causes) and an injury (arising from an external cause) has historically determined coverage and tax treatment in ways that the common language does not anticipate.
Why It Matters in Research
The primary research trap with this term is treating it as a stable, unified concept across sources. It is not. "Sick" means what the governing instrument or statute says it means, and those definitions vary substantially.
In tax research: Federal income tax law distinguishes payments for sickness from payments for personal injury, and the exclusion rules have changed significantly over time. Pre-1983 sick pay exclusion rules differ from current law. Researchers using historical tax materials must be alert to these shifts.
In historical documents — wills, contracts, deeds, affidavits — a recitation that a party was "sick" at the time of execution is a factual predicate for later legal challenges, particularly on undue influence and capacity grounds. The word in such documents is evidence, not a legal conclusion, but courts have read it as opening the door to further inquiry.
Anderson's cross-references direct the researcher toward BENEFITS, CHARITY, DISEASE, INFLUENCE, SUNDAY, WILL, and LANGUIDUS — a clustering that reveals the historical contexts in which "sick" acquired legal salience: charitable provision for the sick, sick-day observance, testamentary circumstances, and the medieval pleading term languidus (a defendant pleading illness to excuse appearance). Each of these branches has its own research pathway.
For employment and benefits research, jurisdictional variation is significant: state sick leave mandates, FMLA leave, and private plan definitions all use "sick" or "sickness" differently. Do not assume that a definition from one source travels to another.
Historical Dictionary Support
Anderson's treats "sick" as a cross-reference hub rather than a defined term, directing readers to related entries rather than offering a standalone definition. This approach is itself informative: it confirms that "sick" had no fixed common law definition but acquired legal meaning through context — through benefit statutes, charitable instruments, testamentary practice, and procedural rules.
The reference to LANGUIDUS is notable and historically significant. Languidus was a formal pleading in which a defendant alleged illness as a reason for failing to appear in court. The linkage of "sick" to this entry suggests that Anderson recognized the procedural dimension of illness claims — sickness not merely as a physical state but as a legally asserted condition with formal consequences.
The reference to SUNDAY reflects another historical context: Sunday observance laws and their exceptions for the sick, who were sometimes exempted from prohibitions on commerce or travel. This is largely obsolete but may be relevant to researchers working in nineteenth-century legal materials.
The reference to WILL, 2 points to testamentary practice, where a testator's physical condition at the time of execution has long been a live legal issue. Historical dictionaries and form books frequently addressed the proper way to describe a sick testator's condition in the will itself and in attestation clauses.
Jurisdictional Note
State law governs most sick leave and sick pay entitlements, and state definitions of "sickness" in insurance contracts are subject to state insurance regulatory frameworks. Federal law governs tax treatment of sick pay and sickness benefits and preempts certain state law in ERISA-governed benefit plans. Researchers should identify whether a given sick pay or sickness benefit question arises under state, federal, or contractual law before selecting sources.
Encyclopedia Cross-Reference
Tax Encyclopedia — Exclusions: Compensation for Injuries and Sickness (tax_56)