Definition
In Saxon and old English law, a measure of length equal to one yard. The unit was derived from the circumference of the human body — the distance around the torso — and belongs to the family of anthropometric measurements from which early English linear standards were drawn. It does not appear as a living unit of measure in modern common law or statutory practice and is encountered almost exclusively in historical legal texts and medieval land or commercial records.
Common Language
Modern common usage (Wiktionary): A band passed under the belly of an animal to hold a saddle or harness in place; by extension, the circumference of anything, including a person's waist; also a small horizontal brace or girder; in graph theory, the length of the shortest cycle in a graph.
Historical common usage (Webster's 1913): A band or strap encircling the body, especially a saddle strap; the measure around the body at the waist or belly; the circumference of any object; a small horizontal brace or girder.
The gap between common and legal meaning here is directional rather than contradictory. In ordinary English, girth refers primarily to a strap that encircles — a physical object — or to the act of measuring circumference. In its sole legal sense, girth is a unit of length: a discrete, fixed measure equal to one yard. A researcher encountering "girth" in a historical legal instrument should not read it as a description of shape, size, or binding equipment but as a stated quantity of linear distance.
Why It Matters in Research
Girth is a fossil term — present in Saxon and early English legal texts, absent from modern doctrine. Researchers working with medieval land grants, market regulations, cloth measurements, or early commercial contracts may encounter it alongside other obsolete anthropometric measures such as the ell, the span, the fathom, and the foot. Recognizing girth as a linear equivalent to the yard prevents misreading it as a descriptive physical attribute of the object being measured.
The unit's derivation from body circumference rather than body length is the critical navigational point. Anthropometric measures in early English law were not standardized in any modern sense; the same term could carry slightly different values across localities and time periods. If girth appears in a document alongside a stated yard measurement, treat them as equivalent; if girth appears alone in a contested historical instrument, note that local variation is possible.
Researchers should also be alert to the term appearing in its contracted or variant forms — Bouvier notes that girth is contracted from "girdeth" — which may affect keyword searching in digitized historical corpora. Searching only "girth" may miss variant spellings in manuscript sources.
There is no meaningful jurisdictional complexity for modern practice because the term carries no operative legal weight today. Its research significance is entirely historical.
Historical Dictionary Support
Black's Law Dictionary (both the first and second editions) and Bouvier's Law Dictionary agree completely: girth is a Saxon-origin measure of length equal to one yard, derived from human body circumference. There is no divergence among the shelf sources on the core definition.
Bouvier adds the most linguistically useful note, tracing "girth" to "girdeth" and equating it with "girdle," and directs readers to ELL for related measure. This cross-reference is worth following: the ell was another body-derived English measure (the length of the arm), and understanding the family of anthropometric units helps researchers calibrate the precision — or imprecision — of measurements in historical documents.
What the historical dictionaries do not address is the range of contexts in which girth appeared in practice. The dictionary entries treat it as a definition only; they provide no guidance on which classes of legal instruments actually used it or how disputes over its exact value were resolved. Researchers should supplement dictionary sources with primary texts on historical English weights and measures for that practical context.