sea-run

The compound adjective 'sea-run' is a modern English formation that transparently combines two native Germanic elements. The first element, 'sea', originates from the Old English 'sǣ', a common Germanic term for a large body of salt water. The second element, 'run', derives from Old English verbs meaning 'to flow' or 'to move swiftly'. In the specific context of ichthyology, 'run' evolved to denote the periodic, directional migration of fish. Therefore, the literal logic of 'sea-run' is "running from the sea," which perfectly describes anadromous fish species that live in the ocean but migrate up freshwater rivers to spawn. This compound exemplifies how English can create precise technical vocabulary through the straightforward combination of familiar, concrete words.

Structure: sea (body of salt water) + run (move quickly/migrate) sea: From Old English 'sǣ', of Germanic origin; related to Dutch 'zee' and German 'See'. Functions as a noun root denoting a large body of salt water. run: From Old English 'rinnan', 'irnan' (to flow, to run), of Germanic origin. In this compound, it functions as a verb root implying movement or migration.