Definition
In Roman and civil law, *avus* is the Latin term for a paternal or maternal grandfather. The term appears in the law of intestate succession and the rules governing degrees of kinship, where precise identification of generational relationships was essential to determining inheritance rights. In the classical Roman system, the *avus* occupied a defined position in the ascending line of a family, one degree above the father (*pater*) and two degrees above the descendant in question.
Why It Matters in Research
This term is encountered almost exclusively in sources drawing on Roman law or the civil law tradition — treatises on the law of descent, intestacy, and family relationships derived from the Corpus Juris Civilis. Researchers working in common law sources will rarely encounter *avus* except in learned commentary or in jurisdictions with civilian heritage (Louisiana, Quebec, Scotland, and South African law). When the term appears in a historical English legal text, it typically signals that the author is reasoning from Roman sources rather than English precedent.
The Institutes reference (Inst. 3, 6, 1) cited consistently across all three source dictionaries points to Justinian's Institutes, Book III, Title 6, which addresses intestate succession among agnatic and cognatic relatives. Researchers consulting that passage will find *avus* used in its direct generational sense as part of the structured hierarchy of heirs. No gap in meaning exists between the classical and the later civil law usage — the term remained stable across centuries of civilian scholarship.
Because *avus* is a term of degree rather than a term of legal relationship in the modern functional sense, it carries no doctrinal weight independent of the succession framework in which it appears. Do not treat it as a standalone legal concept; treat it as a positional marker within a kinship table.
Historical Dictionary Support
All three source dictionaries — Black's (1st ed.), Black's (2nd ed.), and Burrill's — are in complete agreement: *avus* means grandfather in the civil law, each citing Inst. 3, 6, 1 as authority. There is no divergence or evolution across these sources. The brevity of every entry reflects the term's function: it is a vocabulary word rather than a doctrine, and no historical lexicographer attempted to expand it further.
Burrill's entry is notable for including the extended Roman kinship vocabulary in context, situating *avus* within a system that also recognized *proavus* (great-grandfather), *abavus* (great-great-grandfather), and *atavus* (great-great-great-grandfather) — terms that appear in the same titles of the Institutes and Digest. Researchers should be aware that historical dictionaries do not always cross-reference these ascending-line terms together, which can obscure the relational structure a civilian jurist would have understood as a unified table.
None of the source dictionaries address the maternal grandfather specifically. Classical Roman law distinguished between the *avus paternus* (paternal grandfather) and *avus maternus* (maternal grandfather), a distinction that affected succession rights under the older agnatic system. Researchers working with primary Roman sources should attend to this distinction even though the English-language dictionaries collapse it.