Definition of "afoul"

After paying out chain, we swung clear, but our anchors were no doubt afoul of hers.

1840, Richard Henry Dana Jr., chapter 15, in Two Years Before the Mast‎, New York: Harper & Bros., page 137

The atmosphere was soon thick and stifling, and the crews were working their guns with the energy of desperation, when a severe concussion, followed by a harsh and grating sound, told that the ships were afoul.

1849, William F. Lynch, The Naval Officer, Chapter 2, in Graham’s Magazine, Volume 34, Number 3, March 1849

What the devil’s the matter with me? I don’t stand right on my legs. Coming afoul of that old man has a sort of turned me wrong side out.

1851 November 14, Herman Melville, “Chapter 20”, in Moby-Dick; or, The Whale, 1st American edition, New York, N.Y.: Harper & Brothers; London: Richard Bentley

A hemispheric axiom has it that when a dictator falls afoul of Washington, his opponents are emboldened to try to topple him.

1957 December 15, “Still in Business”, in Time

Kings came to hear [Vivaldi’s] concerts but in the end he ran afoul of the Pope’s nuncio and fell out of favor, presumably for neglecting to say Mass […]

1979, Bernard Malamud, chapter 2, in Dubin’s Lives‎, New York: Farrar Straus Giroux, page 79

He committed acts which put him afoul of Empire law, details classified, twenty-six years ago.

1993, Larry Niven, Jerry Pournelle, The Gripping Hand‎, New York: Pocket Books, published 1994, Part 1, Chapter 3, p. 28