Definition
In Roman civil law, a cattle thief; specifically, one who drove or stole animals away from their pastures as a business or habitual practice. The term encompasses the taking of large animals — horses, oxen — from herds, as well as smaller livestock such as swine, sheep, and goats. The classification of an offender as an abigeus, rather than a common thief (fur), turned partly on the scale and systematic nature of the conduct: the Digest treated professional or repeated livestock theft as a distinct and more serious category of offense. Plural: abigei, or less commonly, abigeatores. The corresponding offense is abigeatus.
Common Language
Modern common usage (Wiktionary): A thief who steals livestock in large quantities.
Historical common usage (Webster's 1913): Not listed. The term did not enter general English usage.
The common definition is not wrong, but it misses the legally operative distinction: in Roman law, the abigeus was defined not merely by the quantity of animals taken but by the professional or habitual character of the conduct. An isolated opportunistic taking might still be treated as ordinary theft; it was the pattern of practice that elevated the offense to abigeatus.
Common Confusion
Abigeus is sometimes treated as a direct synonym of abactor. Rapalje & Lawrence equate the two without qualification. The relationship is close but not perfectly symmetrical: abactor tends to emphasize the act of driving away a group of animals, while abigeus carries the additional connotation of habitual criminality. In practice, historical legal dictionaries use them interchangeably, and researchers should cross-search both terms in any corpus.
Why It Matters in Research
This is a Roman law term that migrated into English legal dictionaries largely through the civilian tradition and through Bracton-era borrowings. It has no operative life in modern common law jurisdictions — you will not find it in a modern American or English statute. Its appearance in a source is a signal: the text is either engaging with Roman or civil law directly, drawing on a digest or commentary tradition, or was written in a period when Latinate civilian terminology was standard legal vocabulary.
Researchers encountering abigeus in historical sources should note the following navigational points. First, the definition's internal gradations matter: Black's 2nd edition notes that the classification as abigeus versus common thief depended partly on the number of animals taken, and that smaller animals required a greater number to trigger the designation. That qualifier is absent from some shorter dictionary treatments and from Rapalje & Lawrence's brief entry. Second, the Digest citation (Dig. 47, 14) is the authoritative source; any treatise invoking abigeus without engaging the Digest distinction is likely paraphrasing at remove. Third, the term appears in historical works on English rustling and livestock theft where authors reaching for learned vocabulary used Roman categories — do not assume that appearance in an English source means the Roman law rules applied as positive law.
Corpus researchers should also be aware that variant spellings and inflected forms (abigei, abigeatores, abigeatus) may not be normalized in older scanned texts. Running searches on the root stem abig- is advisable.
Historical Dictionary Support
Black's 1st and 2nd editions are in close agreement, both drawing directly on Digest 47.14. The 2nd edition is marginally more precise, noting that the number of smaller animals required to establish the classification was a variable the Digest addressed — a detail the 1st edition truncates mid-sentence in some reproductions. Rapalje & Lawrence reduce the entry to a cross-reference to abactor, which reflects the synonymy tradition but loses the professional-habitual element that distinguishes abigeus in the Digest itself. No significant point of substantive disagreement exists among the three sources; the variation is in depth, not substance. None of the historical dictionary entries adequately flags that the term carries no operative common law force — a gap researchers should supply from context.
Jurisdictional Note
Roman civil law origin. No jurisdiction applies this term as operative positive law today. Its relevance is historical, comparative, and terminological. Civil law jurisdictions with Roman-law inheritance may retain doctrinal concepts traceable to abigeatus, but the Latin term itself is not in active statutory use.