Definition
An obsolete unit of linear measurement used in old English law, equal to one fathom (six feet). The term appears in early land records and conveyances where distances or dimensions were expressed in this unit. It is a purely archaic term with no modern legal application.
Common Language
Modern common usage (Wiktionary): A constellation of the northern sky, said to resemble a lizard, lying between Cygnus and Andromeda.
Historical common usage (Webster's 1913): "A fathom. [Obs.] Domesday Book."
The astronomical and legal uses share no meaningful relationship. A researcher encountering lacerta in a legal document should not associate it with the constellation of the same name; the legal term refers exclusively to a unit of physical measurement used in land description.
Why It Matters in Research
Lacerta appears in early English land records, surveys, and conveyancing instruments, particularly those predating the standardization of measurement terminology in English legal practice. Researchers working with Domesday Book materials, Norman-era charters, or early common law land records may encounter it as a unit of distance or dimension in property descriptions.
The principal research trap is unfamiliarity with the term's meaning, which can cause misreading of a numerical measurement as some other kind of legal designation. Where a historical instrument states a boundary or dimension in lacertae, the researcher should treat each unit as equivalent to one fathom. Context will usually confirm this: lacerta appears alongside or in place of other linear measures such as perches, furlongs, or rods.
Because lacerta belongs to a pre-standardization era, it may appear inconsistently spelled or abbreviated in manuscript sources. Variant spellings and Latinized forms are common in Norman and early medieval English legal instruments.
This term has no ongoing jurisdictional relevance in any modern legal system.
Historical Dictionary Support
All three source dictionaries agree precisely: Black's (1st ed.), Black's (2nd ed.), and Burrill's each define lacerta as a fathom in old English law, all citing Co. Litt. 4b (Coke upon Littleton). The citation is consistent across editions, though Black's 2nd edition renders it as "40" rather than "4b," likely a typographic variant of the same folio reference. Webster's 1913 corroborates the measurement definition and adds the Domesday Book as an attestation source, confirming that the term's legal use was rooted in the very earliest English land records.
No source provides additional nuance about regional variation, conversion factors beyond "a fathom," or the term's relationship to other period measurements. Historical dictionaries are silent on how lacerta interacted with other contemporaneous units, so researchers needing precision in measurement conversion should consult specialized historical metrology sources rather than relying on legal dictionaries alone.
Burrill's entry is notable for running lacerta directly into the entry for laches without a break, a formatting artifact that could cause confusion in rapid reading of that source.