fault line

American  

noun

Geology.

1. the intersection of a fault with the surface of the earth or other plane of reference.

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fault line British  

noun

1. Also called: fault plane.  geology the surface of a fault fracture along which the rocks have been displaced

2. a potentially disruptive division or area of contention

   Europe remains the main fault line in the Tory Party

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Etymology

Origin of fault line

First recorded in 1865–70

Example Sentences

But Wales's decision to include glass has become a major fault line with industry representatives.

From BBC • Mar. 4, 2026

He astutely flags “medical gatekeeping” as an emerging fault line.

From The Wall Street Journal • Feb. 8, 2026

“The deeper fault line here is not trade flows. It is capital,” wrote Stephen Innes, managing partner at SPI Asset Management, in a Sunday note.

From MarketWatch • Jan. 19, 2026

The Hamaoka plant is located in Omaezaki, Shizuoka prefecture, near a seismic fault line where a massive Pacific earthquake is expected to occur in the coming years or decades.

From Barron's • Jan. 6, 2026

The massacres had happened over two hundred years ago, but the wound they’d made in our cultural history was left raw and festering, like a fault line that may begin trembling again at any moment.

From "The City Beautiful" by Aden Polydoros

Related Words

• rift