an encrusted deposit, especially on a submerged object, as the hull of a ship.

Nearby words

  1. foulage,
  2. foulard,
  3. foulbrood,
  4. fouled-up,
  5. foulie,
  6. foully,
  7. foulmart,
  8. foulmouthed,
  9. foulness,
  10. fouls

Origin of fouling

1350–1400; Middle English foulinge; see foul, -ing1

Related formsnon·foul·ing, adjective



adjective, foul·er, foul·est.

grossly offensive to the senses; disgustingly loathsome; noisome: a foul smell.
containing or characterized by offensive or noisome matter: foul air; foul stagnant water.
filthy or dirty, as places, receptacles, clothes, etc.
muddy, as a road.
clogged or obstructed with foreign matter: a foul gas jet.
unfavorable or stormy: foul weather.
contrary, violent, or unfavorable, as the wind.
grossly offensive in a moral sense.
abominable, wicked, or vile, as deeds, crime, slander, etc.
scurrilous, profane, or obscene; offensive: foul language.
contrary to the rules or established usages, as of a sport or game; unfair: a foul blow.
Baseball. pertaining to a foul ball or a foul line.
limited in freedom of movement by obstruction, entanglement, etc.: a foul anchor.
abounding in errors or in marks of correction, as a printer's proof, manuscript, or the like.
  1. (of the underwater portion of a hull) encrusted and impeded with barnacles, seaweed, etc.
  2. (of a mooring place) involving inconveniences and dangers, as of colliding with vessels or other objects when swinging with the tide.
  3. (of the bottom of a body of water) affording a poor hold for an anchor (opposed to clean).
North England and Scot.. not fair; ugly or unattractive.
Obsolete. disfigured.


in a foul manner; vilely; unfairly.
Baseball. into foul territory; so as to be foul: It looked like a homer when he hit it, but it went foul.


something that is foul.
a collision or entanglement: a foul between two racing sculls.
a violation of the rules of a sport or game: The referee called it a foul.
Baseball. foul ball.

verb (used with object)

to make foul; defile; soil.
to clog or obstruct, as a chimney or the bore of a gun.
to collide with.
to cause to become entangled or caught, as a rope.
to defile; dishonor; disgrace: His reputation had been fouled by unfounded accusations.
Nautical. (of barnacles, seaweed, etc.) to cling to (a hull) so as to encumber.
Baseball. to hit (a pitched ball) foul (often followed by off or away): He fouled off two curves before being struck out on a fastball.

verb (used without object)

to become foul.
Nautical. to come into collision, as two boats.
to become entangled or clogged: The rope fouled.
Sports. to make a foul play; give a foul blow.
Baseball. to hit a foul ball.

Verb Phrases

foul out,
  1. be put out by hitting a foul ball caught on the fly by a player on the opposing team.
  2. be expelled from a game for having committed more fouls than is allowed.
foul up, Informal. to cause confusion or disorder; bungle; spoil.

Origin of foul

before 900; (adj. and noun) Middle English ful, foul, Old English fūl; cognate with Gothic fuls, Old Norse fūll, Old High German fūl; akin to Latin pūs pus, pūtēre to stink, Greek pýon pus; (adv.) Middle English fule, foule, derivative of the adj.; (v.) Middle English fulen, derivative of the adj.

Related forms
Can be confusedfoul fowl

Synonym study

3. See dirty. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for fouling

British Dictionary definitions for fouling



offensive to the senses; revolting
offensive in odour; stinking
charged with or full of dirt or offensive matter; filthy
(of food) putrid; rotten
morally or spiritually offensive; wicked; vile
obscene; vulgarfoul language
not in accordance with accepted standards or established rules; unfairto resort to foul means
(esp of weather) unpleasant or adverse
blocked or obstructed with dirt or foreign mattera foul drain
entangled or impededa foul anchor
(of the bottom of a vessel) covered with barnacles and other growth that slow forward motion
informal unsatisfactory or uninteresting; bada foul book
archaic ugly


  1. a violation of the rules
  2. (as modifier)a foul shot; a foul blow
something foul
an entanglement or collision, esp in sailing or fishing


to make or become dirty or polluted
to become or cause to become entangled or snarled
(tr) to disgrace or dishonour
to become or cause to become clogged or choked
(tr) nautical (of underwater growth) to cling to (the bottom of a vessel) so as to slow its motion
(tr) sport to commit a foul against (an opponent)
(tr) baseball to hit (a ball) in an illegal manner
(intr) sport to infringe the rules
(tr) (of an animal, especially a dog) to defecate ondo not let your dog foul the footpath
to collide with (a boat, etc)


in a foul or unfair manner
fall foul of
  1. to come into conflict with
  2. nauticalto come into collision with
See also foul up

Derived Formsfoully, adverb

Word Origin for foul

Old English fūl; related to Old Norse fūll, Gothic fūls smelling offensively, Latin pūs pus, Greek puol pus

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for fouling
Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with fouling


In addition to the idioms beginning with foul

  • foul one's nest
  • foul play
  • foul up

also see:

  • run afoul of
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.