Definition
A Latin term from old English law denoting an easement — a right held by one party to make limited use of another's land for a specific purpose. The term appears in early medieval legal texts and Latinized legal writing before the anglicized "easement" became the standard term of art. For practical purposes, aisiamentum and easement are functionally equivalent; the Latin form signals age and textual context rather than a distinct legal concept.
Common Confusion
The raw source material supplied to generate this entry contained an erroneous passage describing a principal in the second degree in criminal law — a definition belonging to an entirely different term (aider and abettor) that was apparently concatenated into the source text. That passage has no connection to aisiamentum. Researchers who encounter similarly garbled historical dictionary entries should treat internal inconsistency as a red flag and verify against independent sources.
Why It Matters in Research
Researchers working in early English legal records — plea rolls, manorial court documents, monastic cartularies, or Year Book materials — may encounter aisiamentum where a modern text would simply say easement. The significance is navigational: the Latin form is not a different doctrine, but its appearance marks a document as pre-modern, often pre-sixteenth century, and shaped by the Latinized clerical drafting conventions of medieval English law. Knowing the equivalence prevents researchers from treating the term as a specialized subcategory of property right distinct from the familiar easement framework.
Two practical traps arise. First, the Latin root suggests connection to the French aisement and the concept of "ease" or "convenience," which accurately reflects the functional definition of an easement but can tempt researchers to read the term more broadly than its legal meaning warrants — aisiamentum in legal instruments means easement in the technical sense, not some vague right of comfort or convenience. Second, because the term drops out of English legal usage as law-French and Latin pleading conventions gave way to English, it rarely appears in post-medieval sources. Researchers treating it as a live term in seventeenth-century or later documents should verify that they are not reading an antiquarian quotation or a treatise writer reaching back to older authority.
The corpus connection to easement doctrine is direct: everything a researcher needs to understand the substance of aisiamentum — appurtenance, dominant and servient tenement, acquisition and extinguishment — lives under easement and its related entries.
Historical Dictionary Support
Both Black's editions agree completely: aisiamentum means easement, and both cite Spelman as authority. Henry Spelman's Glossarium Archaiologicum (posthumously published 1664) is the natural source for a term of this character — Spelman devoted that work to archaic and obsolete legal Latin precisely of this kind. No meaningful divergence exists between the two Black's entries; the second edition Supplemental reproduces the first edition definition without variation.
What the historical dictionaries do not supply is any elaboration of the doctrine attached to the term. They treat it purely as a translation problem — aisiamentum equals easement — and leave substantive law to the main easement entry. That is appropriate for a term whose only research value is identification and translation, but it means the dictionaries offer no help with questions about what kinds of rights qualified as aisiamenta in medieval practice or how the concept related to parallel rights such as commons or profits à prendre.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Easements