Definition
To abet is to encourage, incite, or actively assist another person in the commission of a crime. The term carries an exclusively negative legal sense: one who abets does not merely witness or fail to prevent wrongdoing, but affirmatively spurs or supports it. Abetment can take the form of commands, counsel, procurement, or any conduct that emboldens or facilitates the principal offender.
ABET almost always appears in the compound phrase "aid and abet," where it emphasizes the instigating or encouraging dimension of accessory liability, as distinguished from the more physical assistance implied by "aid."
Common Language
Modern common usage (Wiktionary): An act of helping or giving aid; also, fraud or cunning.
Historical common usage (Webster's 1913): To instigate or encourage by aid or countenance, used in a bad sense of persons and acts. Webster's also preserves an obsolete positive sense: to support, uphold, or aid in a good sense.
The legal meaning is narrower and entirely negative. In law, ABET has never carried a neutral or positive sense — it is always tied to criminal complicity. A researcher encountering Webster's obsolete "good sense" usage in a historical document should not read it into a legal context; the legal meaning had already shed that positive register by the time the major common-law dictionaries were compiled.
Common Confusion
AID vs. ABET: These terms are frequently treated as interchangeable, but the 2nd edition of Black's Law Dictionary flags the distinction directly: "aid" and "abet" are "nearly synonymous as generally used," but strictly speaking "aid" does not imply guilty knowledge, while "abet" does. To abet is to knowingly encourage or instigate; to aid may be rendered without awareness that a crime is being committed. The distinction matters most when a defendant's state of mind is at issue — a person who supplies tools or assistance without knowing their criminal purpose may have aided but did not abet.
ABET vs. ACCESSORY vs. ACCOMPLICE: These are related but not identical. ABET describes the conduct (encouraging or inciting). ACCESSORY describes the status (one who assists, often before or after the fact). ACCOMPLICE is the broader modern term for any person who participates in a crime with the requisite mental state. See RELATED TERMS.
Why It Matters in Research
Historical sources consistently define ABET in the criminal context only. Researchers working with older materials — particularly pre-20th century indictments, criminal pleadings, or English common-law sources — should note that the term was technically limited to encouraging or counseling, not to physical assistance. Modern statutes have largely collapsed this distinction under unified "aiding and abetting" or accomplice liability frameworks, but the original doctrinal weight of ABET was on mental encouragement and instigation.
When reading early indictments or grand jury materials, watch for the formulaic phrase "did aid, abet, counsel, and procure" — this was standard pleading language designed to cover all modes of accessory liability. Each word in the chain had a technical role; ABET specifically addressed the encouragement/incitement prong. Treating the phrase as pure boilerplate can cause a researcher to miss arguments about which theory the prosecution actually relied on.
The corpus may also surface materials where ABET appears outside the "aid and abet" pairing, particularly in older English sources discussing abetment of specific crimes. The conceptual structure in those materials maps onto instigation liability more than modern complicity doctrine, and researchers should be cautious about projecting modern accomplice liability rules backward onto those sources.
Historical Dictionary Support
All five source dictionaries agree on the core meaning: to encourage, incite, or set another on to commit a crime. The definitions are strikingly consistent across generations of legal lexicography, which itself signals that ABET had a settled technical meaning in the common law tradition.
Bouvier and Black's (1st ed.) both cite Old Nat. Brev. 21 and Co. Litt. 475 for the proposition that abetting a murder means to command, procure, or counsel it — grounding the term squarely in instigation rather than physical participation. Burrill adds the useful note that ABET is "always taken in a bad sense," directly contradicting the obsolete positive usage preserved in Webster's 1913, and makes clear the term "generally used in connection with the word aid."
Anderson's Dictionary is partially corrupted in the available text but adds "promote the commission of an offense" to the cluster of meanings, and directs readers to ACCESSARY — a cross-reference that reflects the period's doctrinal framework of principal and accessory rather than the modern unified accomplice model.
Black's 2nd edition offers the most analytically precise note among the sources by flagging the guilty-knowledge distinction between "aid" and "abet." That observation is absent from earlier dictionaries and reflects doctrinal refinement over time — researchers relying solely on Bouvier or Black's 1st edition will miss it.
Jurisdictional Note
Most U.S. jurisdictions have codified aiding and abetting as a unified theory of accomplice liability, often eliminating any formal distinction between principal and accessory. Federal law (18 U.S.C. § 2) makes anyone who aids, abets, counsels, or procures a federal offense punishable as a principal. Some states preserve the older conceptual distinction between instigation and assistance in their jury instructions or case law, making the historical meaning of ABET still relevant to statutory interpretation questions.
Encyclopedia Cross-Reference
Criminal Law — Accomplice Liability and Aiding and Abetting (The Law Mind Criminal Law Encyclopedia)