thyroid

Etymology

It is borrowed from New Latin thyroidēs,^[2][3][4][5] or Middle French thyroide, now French thyréoïde,^[4][5][6] from an irregular or altered form of Ancient Greek θυρεοειδής (thureoeidḗs, “shield-shaped”),^[5][7][4][6] which Galen used in χόνδρος θυρεοειδής (khóndros thureoeidḗs, “shield-shaped cartilage”) for the cartilage that forms the Adam's apple.^[6][8][7][9] The Greek adjective is formed from θυρεός (thureós, “oblong shield; stone put against a door”), from θύρα (thúrā, “door”),^{[6][10][11][12]} and -οειδής (-oeidḗs, “-like”).^[10][11] The Greek word for "door" is related to door, and goes back to Proto-Indo-European *dhwer- (“door, doorway”).^[8][7][12]

Earliest recorded meaning

Shield-shaped, of the largest cartilage of the larynx and of the gland beside it: Barnhart finds thyroides in 1693, in a translation from French,^[13] and Etymonline dates it to the 1690s, used of both the cartilage and the gland.^[8] The OED's and Barnhart's 1988 first record is in Monro's Anatomy (1726–41).^[6][11]

Semantic evolution

In English the adjective was applied from the start to both the cartilage and the gland;^[8][6] from 1828 it was also used of the arteries, nerves and veins connected with them.^[6] As a noun, thyroid was short for the thyroid cartilage from 1840 and for the thyroid gland from 1849–52;^[6][11][8] it was also used for thyroid extract,^[6] a powder made from animals' thyroid glands and formerly much used to treat hypothyroidism.^[2][14] In zoology it described a shield-shaped colour marking (1891), and in botany it meant shield-like (1900).^[6] The combining form is thyro-.^[8]

Timeline

• 1693 – thyroides, in a translation from French (Barnhart).^[13]
• 1726–41 – of the thyroid cartilage and gland, in Monro's Anatomy.^[6][11]
• 1828 – of the arteries, nerves and veins near them.^[6]
• 1840 – noun, the thyroid cartilage.^[6][11]
• 1849–52 – noun, the thyroid gland.^[6][11]
• 1891 – in zoology, of a shield-shaped marking.^[6]

Meanings

Noun

1. The thyroid gland, a large endocrine gland at the base of the neck: Her doctor ordered a scan of her thyroid.^[3][2][6]
2. Thyroid extract, a preparation from the thyroid glands of animals, used to treat hypothyroidism.^[2][14][6]
3. The thyroid cartilage, the largest cartilage of the larynx.^[6][2]

Adjective

1. Of, relating to or caused by the thyroid gland: a thyroid disorder.^[2][3]
2. Of or relating to the largest cartilage of the larynx.^[2][6]
3. Shaped like a shield, in anatomy, zoology or botany.^[3][6][14]

Word family

• thyroidal
• thyroidless
• hyperthyroidism
• hypothyroidism
• thyro-
• thyr-
• euthyroid
• antithyroid

Related words

• door
• -oid
• thyroxine

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g Collins English Dictionary (2023), Glasgow: HarperCollins
3. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b c Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
6. ^ a b c d e f g h i j k l m n o p q r s t Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
7. ^ a b c Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
8. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
9. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
10. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
11. ^ a b c d e f g Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
12. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
13. ^ a b Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
14. ^ a b c Stedman's Medical Dictionary, Baltimore: Lippincott Williams & Wilkins