alum

1 of 3

noun (1)

al·​um ˈa-ləm How to pronounce alum (audio)
1
: a potassium aluminum sulfate KAl(SO4)2·12H2O or an ammonium aluminum sulfate NH4Al(SO4)2·12H2O used especially for its astringent and styptic properties
2
: any of various double salts isomorphous with potassium aluminum sulfate
3

alum

2 of 3

noun (2)

: alumnus, alumna
a Yale alum

alum

3 of 3

abbreviation

Did you know?

Is it acceptable to use alum for alumnus or alumna?

The words that we have used to refer to people who have attended or graduated from a school, college, or university have changed a bit over the past several centuries. Traditionally, the word alumnus has been used to refer to a single male, whereas alumna has been used for a single woman. Initially the plural forms were alumni to refer to multiple men (or multiple men and women) and alumnae for multiple women. A little over a hundred years ago the shortened form of alum began to be used to describe a graduate or past attendee of either gender. Although many people feel that alum is informal, it is in increasing use, and we appear to be moving toward a greater acceptance of the word. The plural of alum is alums.

Examples of alum in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Noun
Jeremiah Brent, an HGTV alum who hosted two shows on the network with husband Nate Berkus, is the latest addition to the show, replacing original interior design expert Bobby Berk. Anna Kaufman, USA TODAY, 12 Dec. 2024 In an interview on the 7PM in Brooklyn podcast hosted by NBA legend Carmelo Anthony and The Kid Mero, Woj talked about his hopes of getting an NIL deal for one of the school’s alums, Marques Green. Jason Clinkscales, Sportico.com, 12 Dec. 2024 Stranger Things Broadway play adds season 5 newcomer, Grey's Anatomy alum 7. Ew Staff, EW.com, 11 Dec. 2024 The Golden Bachelor alum Joan Vassos was chosen as the first Golden Bachelorette. Dec. 11, 11:22 a.m. Lexy Perez, The Hollywood Reporter, 11 Dec. 2024 See all Example Sentences for alum 

Word History

Etymology

Noun (1)

Middle English, from Anglo-French alum, alun, from Latin alumen

Noun (2)

by shortening

First Known Use

Noun (1)

14th century, in the meaning defined at sense 1

Noun (2)

1877, in the meaning defined above

Time Traveler
The first known use of alum was in the 14th century

Dictionary Entries Near alum

Cite this Entry

“Alum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/alum. Accessed 21 Dec. 2024.

Kids Definition

alum

noun
al·​um
ˈal-əm
1
: either of two colorless crystalline compounds containing aluminum that are used in medicine (as to check local sweating or to stop bleeding)
2

Medical Definition

alum

noun
al·​um ˈal-əm How to pronounce alum (audio)
1
: either of two colorless or white crystalline double sulfates of aluminum used in medicine internally as emetics and locally as astringents and styptics:
a
: one KAl(SO4)2·12H2O that is a sulfate of aluminum and potassium

called also potassium alum

b
: one consisting of an ammonium aluminum sulfate NH4Al(SO4)2·12H2O

called also ammonia alum, ammonium alum

2
: any of various double salts isomorphous with potassium aluminum sulfate

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