51Թ

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View synonyms for

alum

1

[ al-uhm ]

noun

Chemistry.
  1. Also called potash alum, a crystalline solid, aluminum potassium sulfate, K 2 SO 4 ⋅A 2 (SO 4 ) 3 ⋅24 2 O, used in medicine as an astringent and styptic, in dyeing and tanning, and in many technical processes.
  2. one of a class of double sulfates analogous to aluminum potassium sulfate, as aluminum ammonium sulfate, having the general formula R 2 SO 4 ⋅X 2 (SO 4 ) 3 ⋅24 2 O, where R is a univalent alkali metal or ammonium, and X one of a number of trivalent metals.
  3. (not in technical use) aluminum sulfate ( def ).


alum

2

[ uh-luhm ]

noun

Informal.
  1. an alumna or alumnus:

    Nearly 45 of us alums went on a day trip on the river to celebrate graduation.

alum.

3

abbreviation for

Chemistry.
  1. aluminum.

alum

/ ˈæə /

noun

  1. Also calledpotash alum a colourless soluble hydrated double sulphate of aluminium and potassium used in the manufacture of mordants and pigments, in dressing leather and sizing paper, and in medicine as a styptic and astringent. Formula: K 2 SO 4 .Al 2 (SO 4 ) 3 .24H 2 O
  2. any of a group of isomorphic double sulphates of a monovalent metal or group and a trivalent metal. Formula: X 2 SO 4 .Y 2 (SO 4 ) 3 .24H 2 O, where X is monovalent and Y is trivalent
“Collins English Dictionary — Complete & Unabridged” 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

alum

/ ăə /

  1. Any of various crystalline double salts of a trivalent metal (such as aluminum, chromium, or iron) and a monovalent metal (such as potassium or sodium), especially aluminum potassium sulfate. Alum is widely used in industry as a hardener and purifier, and in medicine as an emetic and to stop bleeding.
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Gender Note

What's the difference between alum, alumnus, and alumna? See alumnus.
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51Թ History and Origins

Origin of alum1

First recorded in 1275–1325; Middle English < Anglo-French, from Latin ū; replacing Old English alefne, ælifnæ, from Old Welsh (compare Medieval Welsh elyf ) < Latin ūԾ- (stem of ū )

Origin of alum2

First recorded in 1875–80; by shortening
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51Թ History and Origins

Origin of alum1

C14: from Old French, from Latin ū
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Example Sentences

Examples have not been reviewed.

“It is a testament to the Office that the Attorney General has appointed one of our alums to this role.”

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The "Saturday Night Live" alum was taken away in a wheelchair.

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The series will take place in “The Office” universe with alum Oscar Nuñez joining the cast.

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Thank you to the Loyola Family and all of our fans/alums for the support this season!

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Netizens lauded the “Jurassic World” alum as the “ultimate gentleman” after he shielded Brown, who wore a miniskirt, from the audience’s view as she got up from a chair.

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Alum Vs. Alumnus Vs. Alumni Vs. Alumna Vs. Alumnae

What’s the difference between alum, alumnus, and alumni?

The informal word alum refers to a graduate of a school, such as a high school or university. It’s a shortening of alumnus or alumna.

In Latin, alumnus specifically refers to a male graduate, and sometimes this distinction is carried into English, with alumna being used to refer to a female graduate. The plural of alumna is alumnae.

The plural of alumnus is alumni (which follows the plural ending construction used in other Latin-derived words, like stimulus and stimuli). Still, alumnus and alumni are both commonly used in a gender-neutral way.

Alum is also used regardless of gender. It’s sometimes pluralized as alums.

Here’s an example of alum and alumni used correctly in the same sentence.

Example: As an alum, you share something with all of the alumni, regardless of when each of you graduated. 

Want to learn more? Read the breakdown of the difference between alumnus and alumni.

Quiz yourself on alum vs. alumnus!

True or False? 

Alum and alumnus are both always used in a gender-neutral way.

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