Definition
Money or value received from labor, business, property, or capital investment. Income is what flows in — the gross receipts or gains derived from a source — without necessarily accounting for what flows out in expenses or costs.
In legal contexts, the term carries different weight depending on the governing instrument or statute:
(1) GENERAL LEGAL MEANING: Any gain or return received by a person from any productive source — including wages, rents, interest, dividends, and business receipts. The essential feature is receipt of value from an external source. Courts and instruments frequently distinguish income from principal or corpus: income is the yield of an asset, not the asset itself.
(2) TRUST AND ESTATE LAW: Income is contrasted with principal. Beneficiaries may hold separate interests — one in the income stream (typically current income beneficiaries), another in the underlying corpus (typically remaindermen). What counts as income versus principal in this context is governed by applicable state law, fiduciary accounting standards, or the instrument itself. The distinction is foundational to trust administration.
(3) TAX LAW: The term takes on its most technical and contested meaning. Federal tax law defines gross income broadly as income from whatever source derived, subject to specific exclusions. What constitutes income for tax purposes has been shaped by constitutional history, statutory text, and judicial interpretation over more than a century. Tax income is not coextensive with economic gain, nor with accounting income.
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Common Language
Modern common usage (Wiktionary): Money one earns by working or by capitalizing on the work of others; money coming into a fund, account, or policy.
Historical common usage (Webster's 1913): That gain which proceeds from labor, business, property, or capital of any kind.
The common understanding of income tracks the general legal definition reasonably well — income is what comes in. The gap emerges at the edges. Common usage treats income as net of obvious costs (most people think of income as what they "take home"). Legal and tax usage is frequently gross — receipts before deductions — unless the instrument or statute specifies otherwise. A researcher using the word loosely in one context may badly misread its meaning in another.
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Common Confusion
INCOME vs. PROFITS: Historical sources draw a consistent and important line. Income, strictly used, refers to gross receipts from a source without deducting expenditures. Profits measure the net gain after both receipts and payments are considered. Burrill and Black both flag this distinction explicitly. In practice, the terms are often used interchangeably in older instruments and decisions, requiring close reading to determine which sense controls.
INCOME vs. REVENUE: Anderson's Dictionary notes that income, when applied to an individual, corresponds to what revenue means for a government or state. The substantive meaning is similar; the word choice signals the actor. Researchers reading public finance materials and private law materials side by side should not treat the terminological difference as substantive.
INCOME vs. PRINCIPAL/CORPUS: In trust and estate contexts, conflating income with the underlying asset is a recurring drafting and interpretation hazard. Rents, interest, and dividends are typically income. The land, bond, or stock generating them is principal. Some receipts — such as stock dividends or proceeds from timber — sit in a gray zone and have generated significant litigation.
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Why It Matters in Research
The word income appears across centuries of legal material in at least three distinct functional contexts — trust law, tax law, and general contract and estate drafting — and these contexts do not share a uniform definition. A researcher who treats the term as self-defining will run into trouble quickly.
In trust materials predating the Uniform Principal and Income Act (and its successive revisions), the income/principal distinction was governed by common law rules that varied by jurisdiction and were frequently unsettled. Court decisions from the nineteenth and early twentieth centuries on what constitutes trust income — particularly on the treatment of corporate distributions and wasting assets — reflect this instability. Do not assume that a judicial definition of income in a trust case carries over to a tax case, or vice versa.
In tax materials, the constitutional dimension is unavoidable. The Sixteenth Amendment's authorization of a federal income tax, ratified in 1913, made the definition of income a constitutional question as well as a statutory one. Pre-1913 materials on income taxation operate under a different framework entirely. The 1913 date is a hard dividing line: research on federal income taxation must be periodized around it.
Older dictionaries are useful for establishing the baseline common law meaning — gross receipts from labor, business, or capital — but they predate the federal income tax system and are silent on its technical requirements. Black's 1st and 2nd editions, both pre-Sixteenth Amendment, define income in terms of its common law and equity meaning. Researchers using these sources for tax questions should do so cautiously.
Jurisdictional variation in trust income definitions is substantial. Some states have adopted the Uniform Fiduciary Income and Principal Act (the 2018 revision of the earlier Uniform Act); others retain older versions; still others apply distinct common law rules. When researching trust income questions, the applicable state statute and any controlling instrument must be identified before general definitions are of much use.
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Historical Dictionary Support
The six historical sources converge on a core definition: income is the return from labor, business, or capital, measured on the inflow side without reference to outgoing expenditures. Burrill is clearest on the strict/loose distinction: strictly, income is gross inflow; loosely, it shades into profit (net gain). Black's first edition echoes Burrill almost verbatim and explicitly sets up the income/profit contrast.
Bouvier adds a useful structural observation — that income applies to individuals while revenue applies to governments — and notes the equivalence between income, rent and profits, and net income in certain estate contexts. Anderson's follows the same equivalence point and cross-references profit and earnings, signaling that the boundary between these terms was contested in the sources he was synthesizing.
Rapalje & Lawrence is the most citation-dense of the group, pointing to specific cases on income of estates, devises, and trust funds. These citations are useful entry points for nineteenth-century equity doctrine but do not address the tax law meaning.
What the historical sources collectively miss: the entire federal income tax dimension. All of these dictionaries were composed before or at the very beginning of the federal income tax era. They reflect equity, trust, and common law usage. The modern researcher relying on them for tax research will find the foundational conceptual vocabulary useful but the substantive content incomplete.
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Jurisdictional Note
For trust and estate purposes, the definition of income is substantially governed by state law, and states vary in which version of the Uniform Principal and Income Act (if any) they have adopted. For federal tax purposes, income is defined by the Internal Revenue Code and interpretive case law, with constitutional limits set by the Sixteenth Amendment. These two bodies of law are parallel systems and do not automatically produce the same result for the same fact pattern.
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Encyclopedia Cross-Reference
Gross Income — Business Income (The Law Mind Tax Encyclopedia §87)
Gross Income — Interest Income (The Law Mind Tax Encyclopedia §101)
Gross Income — Dividend Income (The Law Mind Tax Encyclopedia §92)
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