Definition
A Latin term drawn from Roman civil law and carried into old English legal usage, meaning death or decease. Occasionally extended to mean departure in a procedural or jurisdictional sense. The term appears most often in formal legal instruments — wills, conveyances, and ecclesiastical documents — where death was the operative event triggering a legal consequence, and where Latin remained the drafting language of record.
Common Language
Modern common usage (Wiktionary): Not in general modern English use. Wiktionary traces the Latin root to decedere, meaning to go away or withdraw.
Historical common usage (Webster's 1913): Not listed as an English entry; treated as a Latinate term. The English word "decease" derives directly from the same root and carries the ordinary meaning of death, particularly death as a formal or dignified event.
The gap here is directional rather than semantic: "decease" in modern English is simply a polite synonym for death. Decessus in legal sources was a term of art used precisely because Latin drafting required it, not because it added meaning beyond mors (death). Researchers encountering decessus in primary sources should not read philosophical nuance into the word choice — it is a functional synonym for death in the legal instrument context.
Why It Matters in Research
Researchers working in pre-modern English legal records — particularly wills, probate instruments, feudal tenure documents, and ecclesiastical court records — will encounter decessus as the standard Latin rendering of death or decease. Its importance is positional: the phrase post meum decessum (after my death) was a recurring trigger in testamentary instruments, marking the moment at which bequests, remainders, and executorial authority became operative. Misreading or skimming past decessus can cause a researcher to miss the operative temporal clause in a conveyance or devise.
The secondary meaning — departure, in a procedural sense — is narrower but worth flagging. Burrill notes the usage in 3 Salk. 123 in connection with departure from a jurisdiction or proceeding. This is a distinct legal concept (related to the plea of departure in pleading) and should not be conflated with the testamentary usage. The context will almost always clarify which sense is intended, but researchers should be alert to the procedural meaning when decessus appears in pleading records rather than conveyancing instruments.
Because this term belongs to the Latin legal vocabulary that was phased out of English practice by the Court of Chancery Procedure Act 1852 and subsequent procedural reforms, decessus will be encountered almost exclusively in sources predating the mid-nineteenth century. Post-reform sources in English will use death, decease, or the phrase after the death of without Latin equivalents.
Historical Dictionary Support
Black's (1st and 2nd editions) give the same entry: death and departure, with no additional elaboration. Burrill is the more useful source here. He traces the term to its Digest citation (Dig. 33. 2. 34), connecting decessus to Roman testamentary law, and separately notes its English usage through Fleta — a late thirteenth-century English legal treatise heavily influenced by Roman and canon law, which used post meum decessum in provisions governing what happened to property after the author's death. Burrill also acknowledges the departure sense via 3 Salk. 123.
None of the historical dictionaries elaborate on the distinction between decessus and mors, the more common Latin word for death. For research purposes, the distinction is largely stylistic: both appear in comparable legal contexts, but decessus carried stronger associations with the formal, dignified language of testamentary and ecclesiastical instruments, while mors was more common in criminal, tortious, and procedural contexts.
The maxim appearing in both Black's editions — Decet tamen principem servare leges quibus ipse servatus est (It behoves the prince to keep the laws by which he himself is preserved) — has no apparent textual connection to decessus and appears to be a misplaced or erroneously appended entry in those sources.