Definition
The margin or edge of land bordering the sea. In legal usage, the coast encompasses not only the shoreline itself but also natural appendages of the adjacent territory that rise above the surface of the water — including small islands, reefs, and formations composed of drifted earth and vegetation naturally connected to the mainland. Shoals and formations permanently submerged beneath the water are not included within the legal meaning of coast.
Common Language
Modern common usage (Wiktionary): The edge of the land where it meets an ocean, sea, gulf, bay, or large lake; also more broadly, a side or edge of something, or a region of land.
Historical common usage (Webster's 1913): The seashore or land near it; also formerly used to mean the frontier border or exterior limit of a country generally, and the side or edge of any thing.
The gap between common and legal meaning is narrow but meaningful in one respect: common usage is satisfied by the mere meeting of land and water, while legal usage extends the boundary outward to include natural appendages rising above the water's surface — islands, reefs, and formed deposits — that share a natural connection with the adjacent mainland. The legal definition also expressly excludes permanently submerged shoals, a distinction the ordinary speaker would be unlikely to make.
Why It Matters in Research
The legal definition of coast carries significant weight in admiralty and maritime law, international law, and questions of territorial jurisdiction. Several research traps are worth noting.
First, the inclusion of natural appendages. The principle that small islands and reefs "naturally connected" with adjacent land form part of the coast is not merely descriptive — it bears directly on questions of sovereignty, customs jurisdiction, and the outer limits of territorial waters. Researchers working in admiralty or international law should treat this not as a casual geographic observation but as a jurisdictional boundary marker.
Second, the exclusion of permanently submerged shoals. Bouvier's entry explicitly draws this line. Researchers consulting older maritime cases or customs regulations will find disputes turning precisely on whether a formation qualified as part of the coast, with commercial and jurisdictional consequences attached.
Third, the term's usage in revenue and customs law. Burrill's cross-reference to cocket (a customs-house seal used on coastal trade documents) signals that "coast" in historical statutes often appears in the context of coasting trade — commerce conducted along the coast between domestic ports, as distinct from international trade. The legal meaning of coast in a coasting statute may be narrower or differently bounded than the geographic concept.
Fourth, researchers using pre-twentieth-century sources should be alert to the broader, now-obsolete usage of "coast" to mean simply a frontier or border region (see Webster's 1913), which appears in biblical and early common-law texts without the maritime connotation that dominates modern legal usage.
Historical Dictionary Support
The historical dictionaries are in close agreement on the core definition. Black's (both editions), Bouvier's, and Burrill's all define coast as the edge or margin of land adjacent to the sea, and all extend the term to natural appendages rising above the water. Bouvier's is the most precise, expressly excluding permanently submerged shoals and noting the specific example of the small islands at the mouth of the Mississippi formed by drifted earth and trees — an example drawn from early American territorial and admiralty practice.
Burrill's adds the useful cross-reference to Kent's Commentaries (1 Kent's Com. 29–31), which remains a foundational source for early American treatment of the law of the sea and coastal boundaries.
The Rapalje & Lawrence excerpt in the source material does not contain a definition of coast; the text reproduced addresses an unrelated entry (CLOSE). Researchers should not treat its absence as evidence that Rapalje & Lawrence omitted the term — the source material simply did not capture it.
None of the historical dictionaries address the relationship between coast and the modern concept of the territorial sea or exclusive economic zone. Those frameworks developed after the period these dictionaries primarily reflect, and researchers working in contemporary international or maritime law will need to supplement these sources accordingly.
Jurisdictional Note
In United States law, the precise legal boundary of the coast has been addressed in the context of the Submerged Lands Act and related federal-state disputes over offshore resource rights, which turn on the distinction between coastal and submerged lands. International law defines coastal baselines under the United Nations Convention on the Law of the Sea (UNCLOS), using methods not reflected in any of the historical dictionary sources.