crux

¹ American  

[kruhks] / krʌks /

noun

plural

cruxes, cruces

1. a vital, basic, decisive, or pivotal point.

   The crux of the trial was his whereabouts at the time of the murder.

   Synonyms:

   gist, core, heart, essence

2. a cross.

3. something that torments by its puzzling nature; a perplexing difficulty.

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Crux ² American  

[kruhks] / krʌks /

noun

Astronomy.

genitive

Crucis

1. Southern Cross.

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crux ¹ British  

/ krʌks /

noun

1. a vital or decisive stage, point, etc (often in the phrase the crux of the matter )

2. a baffling problem or difficulty

3. mountaineering the most difficult and often decisive part of a climb or pitch

4. a rare word for cross

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Crux ² British  

/ krʌks /

noun

1. the more formal name for the Southern Cross

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Etymology

Origin of crux¹

1635–45; < Latin: stake, scaffold, or cross used in executions, torment; figurative senses perhaps < New Latin crux ( interpretum ) (commentators') torment, a difficult passage in a text; crucial

Origin of Crux²

< Latin: a cross

Example Sentences

The crux of his argument is better-than-anticipated industry pricing in the first quarter, which “has seemingly moved well ahead of expectations set previously by Micron.”

From Barron's • Mar. 13, 2026

The crux of the issue is that she paid for work on a trust-owned asset before she legally owned it, which is not the same thing as a buyer upgrading their own home.

From MarketWatch • Jan. 19, 2026

And this is the crux of the matter.

From BBC • Jan. 6, 2026

At the crux of the dispute is whether Bartlett can show Nike abandoned the trademark after it failed to renew its registration.

From The Wall Street Journal • Dec. 25, 2025

We thought we were running away from the grown-ups, and now we are the grown-ups: this is the crux of it.

From "Cat's Eye" by Margaret Atwood

Related Words

• bottom line
• core
• essence
• gist
• nub