Definition
A period of three days. In old English law, triduum referred to a fixed span of three days used as a unit of time in legal reckoning — for example, as a prescribed period within which certain procedural acts had to be performed or within which legal consequences attached.
Common Language
Modern common usage (Wiktionary): A period of three days, especially in Roman Catholic liturgy — most familiarly, the Easter Triduum (Holy Thursday through Holy Saturday).
Historical common usage: The term does not appear as a general entry in Webster's 1913, reflecting its status as a Latin ecclesiastical and legal borrowing rather than naturalized English vocabulary.
Editorial note: In common usage, triduum is almost exclusively a liturgical term. The legal meaning is structurally identical — a three-day period — but its function is calendrical and procedural rather than religious. Researchers encountering triduum in historical legal texts should not import ecclesiastical connotations; it operates as a neutral unit of temporal measurement.
Why It Matters in Research
Triduum is a rare term in the Law Mind corpus, appearing almost exclusively in sources treating old English and medieval law. Its practical significance lies not in substantive doctrine but in procedural time-counting: when a text specifies a triduum, it is defining a deadline or window for action. Researchers working with Fleta or similar medieval treatises should recognize that triduum functions alongside analogous time-unit terms (biduum for two days, hebdomada for a week) as part of a Latin temporal vocabulary that governed procedural sequence.
The primary trap is unfamiliarity. A researcher scanning a medieval or early modern legal text may pass over triduum as an ecclesiastical reference and miss its procedural significance. The term signals a hard time boundary, not a liturgical aside.
Because triduum is preserved almost identically across all three source dictionaries and traces to a single passage of Fleta, the corpus is thin. Researchers needing to understand how the three-day period operated in practice should follow the Fleta citation directly rather than expect elaboration in secondary legal dictionaries.
Historical Dictionary Support
All three source dictionaries are in near-complete agreement: triduum means a space of three days in old English law, and all three anchor the definition exclusively to Fleta, lib. 1, c. 31, § 7. There is no divergence on meaning, no doctrinal elaboration, and no indication of evolution across editions.
Burrill adds the most philological texture, identifying the Latin roots (tres, three + dies, day) and labeling the term "L. Lat." — Law Latin — which situates it properly within the specialized legal-Latin vocabulary of English medieval jurisprudence rather than classical or ecclesiastical Latin. This is a useful clarification: the term's legal career is specifically English and medieval, not Roman.
What the historical dictionaries do not provide is any functional context for how a triduum operated procedurally — what acts were governed by it, what consequences flowed from its expiration, or how it compared to other time units in the same system. For that, Fleta itself is the required source.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Time in Law (Historical); Medieval English Legal Procedure.