Definition
A term from medieval Latin denoting an agreement or compact — a mutual undertaking between parties. The word appears in historical legal instruments and glossaries as a variant expression for a binding arrangement or accord, functionally equivalent to terms like *pactum* or *conventio* in the broader vocabulary of Romano-canonical and feudal legal writing.
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Why It Matters in Research
This term exists almost exclusively in historical and antiquarian legal contexts. Researchers are most likely to encounter it in:
- Medieval Latin documents, charters, or instruments, particularly those of Continental origin or Anglo-Norman influence;
- Transcriptions or translations of feudal agreements, ecclesiastical compacts, or manorial records;
- Glossaries appended to older legal treatises that drew on Du Cange's *Glossarium Mediae et Infimae Latinitatis*, the primary lexicographic source for the term.
The practical research value of the entry itself is limited — Black's both first and second editions provide only the bare one-line definition sourced to Du Cange, without elaboration, examples, or connecting doctrine. This signals that the term was already archaic or specialized at the time of those editions' publication and was included for completeness rather than active use.
If you encounter *apatisatio* in a primary source, the operative inquiry is not the word itself but the nature and terms of the underlying agreement it describes. Look to the surrounding instrument for the substantive obligations, parties, and consideration — the same interpretive approach applied to *pactum*, *conventio*, or *concordia* in parallel sources.
Researchers working in medieval English land law, ecclesiastical legal history, or the comparative history of contract should treat this term as a gateway word: its presence confirms you are in historical Latin legal material, and the analytical work begins with the agreement's content, not its label.
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Historical Dictionary Support
Both Black's editions are in complete agreement — the definition is identical across them: "An agreement or compact. Du Cange." Neither edition elaborates, distinguishes subtypes, or connects the term to common law doctrine. The brevity reflects the term's status as a borrowed Latinate archaism rather than a living common law term of art.
Du Cange's *Glossarium* (the full title being *Glossarium Mediae et Infimae Latinitatis*, first published 1678, with later expanded editions) is the foundational reference for medieval Latin legal vocabulary of this kind and is the authoritative source Black's defers to here. Researchers needing deeper context for *apatisatio* in its original documentary settings should consult Du Cange directly.
No standard modern legal dictionary carries the term forward, which itself is informative: *apatisatio* did not survive into active common law or civil law usage as a distinct term of art.
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