Definition
A Latin and Law Latin term appearing in old English legal records, equivalent to the modern "acre" — a unit of land measurement. The term surfaces in medieval English land conveyances, surveys, pleadings, and grants where Latin was the language of record. It is a scribal and documentary form, not a term of art with substantive legal content independent of the land measurement it names.
Common Language
Modern common usage (Wiktionary): A plant of the genus Acer; a maple tree.
Historical common usage (Webster's 1913): No entry for "acer" as an English word; the term was not in common English circulation.
The gap here is total rather than partial. The botanical term "acer" (maple genus) and the legal-Latin "acer" (acre of land) are false cognates — identical in spelling, entirely unrelated in meaning, and separated by context. A researcher encountering "acer" in a botanical or natural history document is reading about trees; a researcher encountering it in a medieval Latin land record is reading about land area. There is no overlap.
Why It Matters in Research
The primary research value of this entry is navigational: "acer" is a variant form that indexes to "acra" and ultimately to the modern "acre," and researchers working with Latin-language English records must recognize all three forms.
Several traps exist for the unwary:
First, Latin legal records from medieval and early modern England were not internally consistent in spelling. The same document — or the same scribe — might write "acer," "acra," "acra terrae," or an anglicized form interchangeably. Corpus searches keyed to only one spelling will miss instances of the others.
Second, the word appears most densely in Domesday-era and post-Domesday conveyancing, manorial surveys, and inquisitions post mortem. Researchers working in those document classes should treat "acer," "acra," and their variants as a single conceptual cluster.
Third, because the actual legal substance lies in the land measurement — how much land was conveyed, taxed, or disputed — the term itself is rarely the issue. The issues are: what standard of acre applied (the acre was not uniform across English counties or time periods), and how the measurement interacted with the bundle of rights being conveyed. The term "acer" points toward those questions but does not answer them.
Historical Dictionary Support
Burrill's Law Dictionary gives a brief entry: "L. Lat. In old English law. An acre. Spelman. See Acra." This is accurate and economical. Burrill correctly identifies the term as Law Latin, roots it in old English legal usage, cites Spelman's Glossarium as authority, and cross-references "Acra" as the primary entry. Nothing in this treatment is in dispute.
What Burrill's entry does not address — as is appropriate for a dictionary of this type — is the practical measurement problem: the English acre was subject to local variation (the statute acre, the customary acre, the Cheshire acre, among others), and documents using "acer" do not on their face disclose which standard applies. That question belongs to historical metrology rather than legal lexicography, but researchers should be aware that the word's precision in a document is limited to identifying the unit, not fixing its size.
No other shelf source in the current corpus carries an entry for "acer" as a legal term. The term is sufficiently archaic and sufficiently narrow that its absence from later dictionaries is unremarkable.
Jurisdictional Note
This term is specific to English legal Latin and appears almost exclusively in records from England and, by derivation, early colonial jurisdictions that inherited English land-record conventions. It does not appear as a term of art in modern common law jurisdictions, which use "acre" exclusively.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: ACRA