Definition
In old English law, the act of alienating real property to a religious house, corporation, or other ecclesiastical body so that it passed into "dead hands" — that is, into permanent institutional ownership from which it could not be transferred by ordinary conveyance or inheritance. The term is the Latin and Law Latin form of what English sources call amortization or amortisement.
The word names both the act of the transfer and the legal condition that resulted: once land entered mortmain through amortizatio, it was effectively frozen in the hands of the receiving body, incapable of the feudal services and incidents — reliefs, wardships, marriages — that the crown and mesne lords expected when land passed between natural persons. Because institutional owners did not die, land held in mortmain never escheated, never produced an heir, and never triggered the profitable incidents of tenure.
Common Confusion
AMORTIZATIO vs. AMORTIZATION (MODERN): The two terms share a root but refer to entirely different legal concepts across different eras. Amortizatio describes the medieval act of alienating property into perpetual institutional ownership — a transaction courts and statutes sought to restrict. Modern amortization describes the systematic reduction of a debt balance or the spreading of an asset's cost over its useful life — a financial planning and accounting concept. No substantive connection exists between the two meanings beyond their shared Latin origin.
Why It Matters in Research
This term appears almost exclusively in medieval and early modern English legal sources, and almost always in Latin or Law Latin form. Researchers working in pre-modern English property records, ecclesiastical sources, or treatises on feudal tenure should treat amortizatio as a term of art pointing toward the broader body of mortmain law. The key statutes — the Statute of Mortmain (De Viris Religiosis, 1279) and its successors — are referenced in English-language sources under mortmain, amortisement, or mortmain alienation rather than under this Latin form, so a search confined to amortizatio will retrieve only a fraction of the relevant material.
A second research trap: in modern financial and property law, amortization refers to the gradual paying down of a debt or the depreciation of an intangible asset over time. That modern meaning is entirely unrelated to amortizatio. The Latin form signals the medieval ecclesiastical property sense; the anglicized modern form signals the financial sense. When indexing or searching a corpus that spans centuries, this divergence can produce false connections if terms are not disambiguated by period and context.
The term also connects to the licensing system that developed in response to mortmain restrictions. The crown and, later, Parliament could grant a license to amortize (licentia mortizandi or licentia amortizandi), permitting a specific transfer into ecclesiastical or corporate hands notwithstanding the mortmain prohibition. Records of such licenses are a distinct documentary category in medieval English chancery and patent rolls.
Historical Dictionary Support
Burrill's Law Dictionary gives a compact and accurate entry: amortizatio is defined as "[a]lienation in mortmain; (translatio in manum mortuam;) amortization, or amortisement," citing Spelman. The parenthetical Latin phrase — translatio in manum mortuam, meaning transfer into dead hand — is the clearest gloss on the term's operative meaning and is worth preserving when reading Burrill in context.
Burrill's reliance on Spelman (Henry Spelman's Glossarium Archaiologicum) is appropriate: Spelman remains one of the principal authorities on the vocabulary of medieval English feudal and ecclesiastical law, and his treatment of mortmain-related terminology is more expansive than most later dictionaries. Researchers who need fuller doctrinal context beyond Burrill's entry should consult Spelman directly, as well as Blackstone's Commentaries (Book II, Chapter 18) for the common law framework and Coke's commentary on feudal tenure.
What the historical dictionaries collectively do not address is the procedural dimension: the licensing apparatus, the role of the Inquisition ad quod damnum (the inquiry required before a mortmain license would issue), or the statutory evolution from 1279 onward. These are matters for encyclopedia and treatise sources rather than dictionary entries, but researchers should be aware the dictionary definition captures only the transactional label, not the surrounding legal machinery.
Jurisdictional Note
Amortizatio and the mortmain doctrine it names were distinctively English and developed within the English feudal tenure system. Scotland, Ireland, and continental jurisdictions had analogous but distinct rules governing ecclesiastical land-holding. Researchers should not assume that continental sources using cognate terms carry the same technical English legal meaning.