Definition
In Scots law, a tack is a contract by which the use of land or another immovable subject is let to a lessee — called a tacksman — for a fixed period in exchange for a yearly payment known as the tack duty. The payment could take the form of money, a share of the land's produce, or services. The term is functionally equivalent to a lease and is also known as an assedation.
The word is occasionally encountered in older Anglo-American sources, particularly in discussions of Scots legal institutions, feudal tenure, or in historical materials from jurisdictions with significant Scottish legal influence. In modern usage outside Scotland, tack as a distinct legal term has largely disappeared in favor of lease or tenancy.
Common Language
Modern common usage (Wiktionary): A small nail with a flat head; a thumbtack; a loose temporary stitch in sewing; the lower forward corner of a sail; a sailing vessel's heading relative to the wind; a direction or course of action.
Historical common usage (Webster's 1913): A stain or tache (obs.); a peculiar flavor or taint, as in a musty quality (obs. or colloquial).
The legal meaning shares nothing with the nail or sewing senses that dominate modern everyday English. The one thread of overlap is indirect: the common expression "take a different tack" — meaning to try a new approach — derives from the sailing sense of tack as a course or heading, not from the legal meaning. Researchers encountering tack in a historical legal document should not import any of these common meanings; the legal context is purely one of land tenure and contract.
Common Confusion
Tack (the Scots lease) should not be confused with tacking as it appears in Anglo-American property and mortgage law. In that distinct doctrine, tacking refers to the practice of joining successive periods of adverse possession, or successive mortgage interests, to satisfy a legal threshold — most commonly the statutory period for adverse possession. The two uses of the word are etymologically unrelated in legal operation. A researcher finding tack in a Scottish or feudal context is dealing with a lease; a researcher finding tacking in an American adverse possession or lien priority context is dealing with a joinder doctrine. The encyclopedia cross-reference above addresses the latter.
Why It Matters in Research
The primary research trap is conflation. Tack and tacking appear in historically adjacent materials, and a researcher scanning older digests or treatises may encounter both without clear contextual markers distinguishing the Scots lease from the adverse possession or mortgage joinder doctrine.
When working with Scottish legal materials, colonial records from regions with Scots settlers, or early American sources drawing on Scots institutional writers (Erskine, Forbes, Stair), tack will appear in its lease sense. Erskine's Institutes and Forbes's Institutes are the key foundational texts. In those sources, tack duty is the rent reserved under the lease, and the tacksman is the tenant — a usage that persisted with social significance in Highland estate management well into the eighteenth century.
In English and American materials, tack almost never appears as a synonym for lease. When it does surface in those sources, it is either a direct quotation from a Scots authority or a historical curiosity. Do not read it as a term of art in English common law without verifying that the source is engaging with Scots law.
The Law Mind corpus is likely to contain tack primarily in two contexts: (1) historical property and feudal tenure materials discussing Scots law, and (2) adverse possession entries where tacking as a joinder doctrine is addressed. These contexts are distinct and should be researched separately.
Historical Dictionary Support
Bouvier and Burrill are in close agreement. Both define tack as a Scots law contract of letting — essentially a lease — and both note the tack duty as the reserved rent. Burrill adds the synonym assedation and cites Forbes's Institutes directly. Bouvier cites Erskine's Institutes. Neither source attempts to extend the term into English common law usage, which is the correct approach; tack as a lease is a Scots institution without a meaningful English analogue beyond the word lease itself.
Neither dictionary addresses the adverse possession sense of tacking, which is a separate development in Anglo-American law and not derived from the Scots lease. Historical dictionaries of the nineteenth century are largely silent on tacking as a property joinder doctrine under that label, which means researchers relying solely on period dictionaries may not find adequate coverage of the adverse possession doctrine — another reason to consult the encyclopedia entry directly.
Jurisdictional Note
Tack as a lease is specific to Scots law and has no operative meaning in English or American common law jurisdictions. In Scotland, the concept has been substantially modified and in many respects superseded by modern landlord and tenant legislation. Researchers working in contemporary Scots law should treat the historical dictionary definitions as descriptive of a historical institution rather than current doctrine.
Encyclopedia Cross-Reference
Adverse Possession — Tacking of Successive Possessors (The Law Mind Property Law Encyclopedia)