Definition
A historical English legal measure referring to the quantity of a ton or tun of cargo space within a ship's freight or bulk, used as the unit upon which tonnage (or tunnage) dues were assessed and paid to the Crown. In practice, tonnetight designated the amount of space a single tun of cargo occupied in a vessel's hold — the standardized unit that determined a ship's tax liability under the medieval English system of tunnage duties.
Why It Matters in Research
Tonnetight is a term of exclusively historical significance. Researchers will encounter it only in medieval and early modern English sources dealing with maritime taxation, port records, customs rolls, and trade regulation. Several research traps are worth flagging:
First, the term is obsolete and does not appear in modern maritime or customs law. Any research question involving modern tonnage dues, vessel registration tonnage, or port fees will not be served by this term and should instead begin with the modern statutory framework governing vessel measurement.
Second, researchers should be careful not to conflate tonnetight with tonnage as it is used today. Modern tonnage is a volumetric or weight-based measurement used for vessel classification and registration; tonnetight was a unit tied specifically to the levy of a royal tax, not a general measurement standard.
Third, the Black's Law Dictionary (2nd Ed.) entry contains what appears to be an incomplete continuation — the text breaks off mid-sentence with "In old Scotch law. A" — suggesting the original source may have contained a distinct Scottish usage that was not fully reproduced. Researchers working with Scottish medieval maritime records should treat the historical dictionaries as incomplete on this point and consult primary Scottish sources independently.
Fourth, Burrill's Law Dictionary attributes the term to a Patent Roll citation from the reign of Richard II (Pat. 2 Ric.), which places the term's documented use in the late fourteenth century. Researchers working in this period may wish to consult the Patent Rolls directly for contextual usage.
Historical Dictionary Support
All four source dictionaries — Black's (1st and 2nd editions), Bouvier's, and Burrill's — are in close agreement on the core definition: tonnetight is the quantity of a ton or tun in a ship's freight or bulk, serving as the basis for tunnage payment to the king. The consistency across sources suggests they share a common origin, likely Cowell's Interpreter, which is cited in Black's and Bouvier's as the primary authority. Burrill alone adds a primary source citation (Pat. 2 Ric.), grounding the term in the Patent Roll records of Richard II's reign and giving it a firmer evidentiary anchor than the other entries provide.
None of the historical dictionaries elaborate on how tonnetight was measured in practice, how the tun was standardized, or how the levy was administered. Researchers seeking procedural or administrative detail will find the dictionary record thin and should look to treatises on medieval English customs law and port administration.
The truncated Black's (2nd Ed.) entry hints at a Scottish variant but provides no definition for it. This is a gap in the historical record as reproduced in the standard reference dictionaries.
Jurisdictional Note
Tonnetight is a term of old English law, with a possible but undefined usage in old Scots law suggested by the incomplete Black's (2nd Ed.) entry. It has no recognized place in the law of any modern jurisdiction.