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alum

noun · verb

Simple meaning

A double sulphate of aluminum and potassium that is used as an astringent.

Pronunciation

Say it like this:

aluhm

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US device voice
IPA pronunciation (US)

ˈæləm

This word is pronounced essentially the same in American and British English, so one transcription covers both.

IPA (International Phonetic Alphabet) is a standard way of writing speech sounds.

Word Review

Definition

Everyday modern meanings first, grouped by part of speech.

noun

  1. A double sulphate of aluminum and potassium that is used as an astringent (among other things)

  2. An astringent salt, usually occurring in the form of pale crystals, much used in the dyeing and tanning trade and in certain medicines, and now understood to be a double sulphate of potassium and aluminium (K₂SO₄·Al₂(SO₄)₃·24H₂O).

  3. canadaus

    A past attendee or graduate (of any gender) of a college, university or other educational institution.

  4. inorganic chemistry

    Any similar double sulphate in which either or both of the potassium and aluminium is wholly or partly replaced by other univalent or tervalent cations.

verb

  1. transitive

    To steep in, or otherwise impregnate with, a solution of alum; to treat with alum.

Word at a Glance

Difficulty
C1 · Advanced (estimated)
Frequency
Uncommon
Formality
Technical

Word Aura™

How this word commonly comes across.

Aura for this meaning

This meaning: A double sulphate of aluminum and potassium that is used as an astringent (among other things)

Used this way, alum is a reasonably familiar word that usually carries little praise or criticism of its own. It usually sounds natural in a wide range of settings.

Emotional tone
Neutral
Formality
Neutral
Intensity
Not strongly marked
How common
Moderately common
Connotation
Matter-of-fact
Usage feel
Neutral and straightforward

Nearby words

  • potassium alum , rarer, so it draws attention

Word Aura describes common impressions, not a measurement. Tone changes with sentence, speaker, relationship and situation.

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Common Patterns and Combinations

How this word naturally appears with others.

Double / astringent

chrome alumpotassium alumammonium alumpotash alumiron alum

Steep

alum solution

Other combinations

alum rockalum shale

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Word Family

Related forms, grouped by how they connect.

Compound terms

Established multiword terms.

  • ammonia alumnounCompound term

    A white crystalline double sulfate of aluminum: the ammonium double sulfate of aluminum.

  • ammonium alumnounCompound term

    A white crystalline double sulfate of aluminum: the ammonium double sulfate of aluminum.

More about this wordSynonyms, forms, origin

Synonyms

Sense: double sulphate of aluminum and potassium that is used as an astringent (among other things)

potassium alumRare

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Dictionary data from Wiktionary via the Free Dictionary API. Simple meanings, combinations and word intelligence are built from verified reference data, no AI is used to load this page.