amyloid

Etymology

It is borrowed from German, where Vogel and Schleiden coined it in 1839,^[2][3] from Latin amylum (“starch”) and the suffix -oid.^[2][3] Merriam-Webster treats it as an International Scientific Vocabulary formation from amyl- and -oid.^[4] The Latin noun is from Ancient Greek ἄμυλον (ámulon, “fine meal, starch”),^[3][5][2] the neuter of the adjective ἄμυλος (ámulos, “not ground at the mill”), formed from ἀ- (a-, “not”) and μύλη (múlē, “mill”);^[3][5] the OED gives the second part as μύλος (múlos, “mill”).^[2] Etymonline traces the word for the mill to Proto-Indo-European *mele- (“to crush, grind”).^[3] The suffix goes back to -οειδής (-oeidḗs, “like”).^[5]

Earliest recorded meaning

Resembling starch: Merriam-Webster dates this sense of the adjective to 1840,^[4] Etymonline to 1843,^[3] and the OED's first quotation is from Henfrey's Elementary Course of Botany (1857).^[2]

Semantic evolution

The word was first a term of botany and chemistry for starch-like substances.^[2][6] From 1859 it was applied in pathology to a kind of degeneration of organs and to the substance deposited in it, which was at first thought to be related to starch;^[2][6] this is the sense that survives most widely, for a waxy deposit made mainly of protein, as in Alzheimer's disease.^[7][8][9] As a noun it meant a starch-like substance or a member of the group of carbohydrates that includes starch and cellulose (1872, in Huxley),^[2][3] and later the protein deposit itself;^[7][6] the noun's protein sense is dated 1866 in Merriam-Webster's Collegiate.^[7]

Timeline

• 1840 – adjective, resembling starch.^[4]
• 1841 – noun, a starchy food or starch-like substance.^[4]
• 1859 – adjective, in pathology, of a degeneration of organs and the substance it produces.^[2]
• 1866 – noun, the waxy protein deposit in diseased tissue.^[7]
• 1872 – noun, a substance akin to starch, any of the carbohydrates such as starch and cellulose.^[2][3]

Meanings

Noun

1. A waxy, translucent substance made mainly of protein that is deposited in organs and tissues in certain diseases, as in amyloidosis: Clumps of amyloid were found in the patient's kidneys.^[7][8][9][6]
2. Any substance that resembles starch.^[8][9][4][2]

Adjective

1. Resembling or containing starch; starch-like.^[8][9][4][2]
2. Relating to or marked by deposits of amyloid: amyloid plaques.^[4][6][2]

Word family

• amyloidosis

Related words

• amyl
• amylase
• -oid
• mill

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ 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
7. ^ a b c d e Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster
8. ^ a b c d The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin
9. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins