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Etymology and origin of the English word alum

alum1 mineral salt

Confidence
Established
Formation
Borrowing
First attested
1398 before 1398, John Trevisa's translation of Bartholomaeus Anglicus
Borrowed from
Anglo-Norman alum via Middle English
Ultimate origin
Latin alūmen

Pronunciation

Etymology

The mineral salt is inherited from Middle English alum, also alom and alim,[2][3] borrowed from Anglo-Norman alum, also alume,[3][4][5] and Old French alum, alun,[6][7][8] now alun,[3][9] from Latin alūmen (“alum”).[3][6][10][7] The Anglo-Norman word is recorded from the mid 12th century.[11] Etymonline traces the Latin word to Proto-Italic *alu- (“bitter substance”), so that it is literally "bitter salt", cognate with Ancient Greek ἀλύδοιμος (alúdoimos, “bitter”);[6][9] Barnhart and Klein relate it further to Old English ealu (“ale”) and so to ale,[7][9] and Barnhart to Proto-Indo-European *alu- (“bitter”).[7] The Oxford dictionaries relate it to alūta (“tawed leather”).[12][13][7] Old English had its own word for alum, ælifn, which the Middle English word replaced.[3][5] The Latin word also gave allume and alumbre.[3]

Earliest recorded meaning

An astringent mineral salt: before 1398, in John Trevisa's translation of Bartholomaeus Anglicus,[3][2] where iron is smeared with alym.[2] Barnhart dates the word to 1373,[14][7] and the OED notes an earlier record of 1228 in an English customs account that may show the Anglo-Norman or the Middle English word.[3]

Semantic evolution

In Middle English the word named common or potash alum, and also served as a general term for alum-bearing minerals and similar salts.[2] Chaucer used it twice.[15] From 1600 it was used for any of various substances resembling it,[3] and in chemistry for a whole series of double sulphates of the same crystal structure.[3][12] A verb alum, to treat or coat with alum, is recorded from before 1425.[3] Johnson (1755) described alum as a mineral salt of acid taste, leaving a sweetish sense in the mouth with much astringency.[16] In 19th-century American slang the alum meant exactly the thing wanted.[17]

Timeline

  • 1398 – an astringent mineral salt.[3][2] Barnhart dates it to 1373.[7]
  • c. 1425 – verb, to treat or coat with alum.[3]
  • 1600 – any substance resembling alum; in chemistry, any of a series of double sulphates.[3]

Meanings

Noun

  1. A colourless crystalline double sulphate of aluminium and potassium, used as a mordant in dyeing, in tanning and paper-making, and in medicine as an astringent and styptic.[18][4][3]
  2. Any of a group of double sulphates of the same crystal structure, in which other metals take the place of aluminium or potassium.[18][4][12]

Verb

  1. To treat, soak or coat with alum.[3][12]

Word family

  • alumina
  • alumroot
  • alum rock
  • potash alum
  • chrome alum
  • ammonia alum

alum2 former student

Confidence
Established
Formation
Clipping
First attested
1877
Ultimate origin
Latin alumnus

Pronunciation

Etymology

The word for a former student is a clipping of alumnus and alumna.[3][4][5]

Earliest recorded meaning

A former student of a school or university: 1877, in a translation of a text by J. H. Balfour.[3][4] Merriam-Webster's Collegiate dated it to 1930.[19]

Semantic evolution

An earlier alum, taken from Latin alumnus, was used once in 1683 for a foster child or protégé, in figurative use.[3] The modern clipping is chiefly American,[3] and is used for a graduate of either sex.[20][4]

Timeline

  • 1683 – a foster child, a protégé (now obsolete).[3]
  • 1877 – a former student; an alumnus or alumna.[3][4]

Meanings

Noun

  1. (informal, chiefly US) A former student or graduate of a school, college or university, of either sex; an alumnus or alumna.[4][3][20]
  • aluminiferous
  • aluminize
  • aluminite
  • aluminous
  • alunite
  • alunogen
  • ale
  • aluminium
  • alma mater

Usage notes

Most standard dictionaries call alum for a graduate informal;[20] Grammarphobia recommends it for a single graduate whose sex is unknown, though not for formal writing.[20]

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e Kurath, Hans; Kuhn, Sherman M.; Lewis, Robert E., eds. (1952–2001), Middle English Dictionary, Ann Arbor: University of Michigan Press; online edition ed. Frances McSparran et al. (2000–2018)
  3. ^ a b c d e f g h i j k l m n o p q r s t u v w Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  4. ^ a b c d e f g h Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  5. ^ a b c Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  6. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  7. ^ a b c d e f g Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  8. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  9. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  11. ^ Anglo-Norman Dictionary (AND2), Aberystwyth University, anglo-norman.net (2nd ed., 2005–)
  12. ^ a b c d Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  13. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  14. ^ Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
  15. ^ Benson, Larry D., Glossarial Concordance to Middle English (Chaucer, Gower), Johns Hopkins University, github.com/jhu-digital-manuscripts/gcme
  16. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  17. ^ Green, Jonathon (2010), Green's Dictionary of Slang, London: Chambers; digital ed. 2016–, https://greensdictofslang.com
  18. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins
  19. ^ Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster
  20. ^ a b c d O'Conner, Patricia T.; Kellerman, Stewart, The Grammarphobia Blog, grammarphobia.com, p. "Is that an “alum” on your bib?", 13 July 2018

Related etymologies

Cite this entry

“Alum.” Etymologically, 1 Nov. 2026, etymologically.com/en/alum. Accessed 1 Nov. 2026.

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