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

The fault line exposed now is that private credit is being offered to retail investors and wealthy individuals whose liquidity preferences are different from sophisticated, more patient institutional investors.

From MarketWatch • Feb. 26, 2026

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

From The Wall Street Journal • Feb. 8, 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

You don’t know that when a memo arrives to confirm the assignment, some deep and unseen fault line in your life has begun to tremble, that some hold is already starting to slip.

From "Becoming" by Michelle Obama

Related Words

• rift