afoul

American  

[uh-foul] / əˈfaʊl /

adverb

1. in a state of collision or entanglement.

   a ship with its shrouds afoul.

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idioms

1. run / come / fall afoul of,

   1. to become entangled with.

      The boat ran afoul of the seaweed.

   2. to come into conflict with.

      The business had fallen afoul of the new government regulations.

afoul British  

/ əˈfaʊl /

adverb

1. (usually foll by of) in or into a state of difficulty, confusion, or conflict (with)

2. (often foll by of) in or into an entanglement or collision (with) (often in the phrase run afoul of )

   a yacht with its sails afoul

   the boat ran afoul of a steamer

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Etymology

Origin of afoul

An Americanism dating back to 1800–10; a- ¹ + foul

Explanation

If something goes afoul, it goes badly wrong. When a prank falls afoul of the law, it crosses the line from just a joke to something much more serious. Use the adjective afoul to describe things that conflict or clash. If a politician goes afoul of the rules about using taxpayer money for person items, she's bound to pay for it in votes. Likewise, a party guest might accidentally go afoul of the etiquette about how much candy to grab from a fallen piñata. The original nineteenth century meaning of afoul was nautical, describing tangled ropes or lines on a ship.

Example Sentences

Ahead of the game, the FAA warned drone operators that they could get their drone seized, face federal criminal charges and fines of up to $100,000 if they run afoul of these restrictions.

From Los Angeles Times • Jun. 14, 2026

But Rossetti’s comments ran afoul of his boss, the Catholic archbishop of Washington, D.C., who announced Wednesday he had “removed” Rossetti from his position as an exorcist.

From Slate • Jun. 8, 2026

Whatever work your business hires your child to do, make sure it does not run afoul of any federal or local labor laws.

From MarketWatch • May 26, 2026

Over time, the promise of fair pricing became enmeshed with an even loftier assurance: by partnering with “ethical factories,” it would sell better-made clothing in a way that didn’t run afoul of the customer’s morals.

From The Wall Street Journal • May 23, 2026

The tangent problem and the area problem both ran afoul of the same difficulties with infinities and zeros.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife