isthmus

Etymology

It is borrowed from Latin isthmus,^[2][3][4][5] from Ancient Greek ἰσθμός (isthmós, “neck, narrow passage, neck of land between two seas”),^[2][4][6] especially that of Corinth.^[2][7] The further origin of the Greek word is uncertain.^[3][8][6][4] A derivation from εἶμι (eîmi, “to go”) with a suffix -θμο- (-thmo-) has been proposed, comparing ἴθμα (íthma, “a step, movement”),^[6][4][7] and Merriam-Webster Unabridged and Klein also compare Old Norse eið (“strait of land”).^[9][6][7] Beekes objects that the -σ- stays unexplained, reports Chantraine's view that the word was adapted from a local loan, and marks it as perhaps Pre-Greek,^[7] and the American Heritage Dictionary likewise allows a pre-Greek substrate origin.^[10]

Earliest recorded meaning

A narrow strip of land between two bodies of water, linking two larger land masses: first in R. Eden's translation of Peter Martyr's Decades, 1555.^[2][3][9] Etymonline gives the 1550s.^[4]

Semantic evolution

English used it from the first as a general geographical term, not only of Corinth.^[2] An attempt at a native equivalent, strictland, is recorded from the 1570s in Holinshed, according to Etymonline.^[4] The word soon went figurative: the OED's first such use is in S. Daniel in 1601,^[2] and Johnson (1755) quotes Cowley's "weak built isthmus" of life and Pope's "isthmus of a middle state".^[11] From 1706, in Phillips's New World of Words, it also named a narrow connecting part in anatomy, zoology and botany, such as the passage between the mouth and the pharynx, or the band of tissue between the two lobes of the thyroid.^[2][5]

Timeline

• 1555 – a narrow neck of land between two bodies of water.^[2][3][9]
• 1601 – figuratively, of a narrow connection.^[2]
• 1706 – in anatomy, zoology and botany, a narrow part connecting two larger parts.^[2][5]

Meanings

Noun

1. A narrow strip of land with water on both sides, connecting two larger land areas: The engineers cut a canal across the isthmus to shorten the voyage.^[12][9][2]
2. (anatomy) A narrow band of tissue joining two larger parts of a structure, or a narrow passage joining two cavities.^[12][9][5]
3. The fleshy area on the throat of a fish, between the gills.^[9]

Word family

• isthmoid
• isthmian
• isthmic

Usage notes

Merriam-Webster Unabridged gives the pronunciation with a silent th first, and calls the one with /t/ chiefly British.^[9] The plural is isthmuses or, less often, isthmi.^[12][5]

References

1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
4. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
5. ^ a b c d e Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
6. ^ a b c d Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ a b c d Beekes, Robert S. P. (2010), Etymological Dictionary of Greek, with the assistance of Lucien van Beek, Leiden Indo-European Etymological Dictionary Series 10, Leiden; Boston: Brill
8. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
9. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
12. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins