An idiom is a commonly used phrase or expression that doesn't follow the usual language patterns or that has a meaning other than the literal. Phrases that, when dissected, don't seem to make much sense, are often idiomatic. For example, when you read “They can't come up with the answer,” or “The director stood up for herself,” or “The play ended with a bang,” you probably know what the writer means. But if you look up the definition of each word in these phrases, the meaning of the expression as a whole does not make sense.

Idioms aren't something you memorize. If English is your native language, you already know thousands of idioms, so you don't question what they mean. But if you try to learn the idioms of another language, or if you are trying to learn English, you'll find that idioms can be a real challenge.

Figurative idioms

Figurative idioms are expressions so common you don't question their source: let the cat out of the bag, he has a monkey on his back, it's the straw that broke the camel's back, you're splitting hairs, the ball's in your court, and so on. Many figurative idioms have become clichés and empty of true meaning. You can use them occasionally—but don't overuse them.

Prepositional idioms

The most common idiom is an expression that depends on the choice of a particular preposition. The choice may seem arbitrary. For example, why do we say “She put up with him” rather than “She put on with him”? “At home” rather than “in home”? Why is it sick of him rather than “sick from him”? Why do we get in a car but on a boat? There is no logical reason; the expressions are idiomatic. Notice in addition that many words take different prepositions to form different idioms. For example, to wait on someone is different from to wait for someone .

Prepositional idioms don't follow rules you can memorize. Fortunately, you can usually rely on your ear and your experience. When you're in doubt about the right preposition for an expression, check a dictionary. The entry for a word sometimes gives you a phrase showing which preposition to use. When the word is associated with several idioms, they are often listed at the end of the entry.

Examples of prepositional idioms

Although far from complete, this list illustrates the importance of prepositions in forming idioms.

  • accountable for (responsible for)—I am accountable for the errors in the book.

  • accountable to (answerable to someone)—I am accountable to the board of directors.

  • adapt from (a model)—He adapted the design from one he had seen in Europe.

  • adapt to (a situation, an environment)—The children soon adapted to the new school.

  • agree on or upon (something)—We agreed on a date for the meeting.

  • agree to (do something)—We agree to pay the damages.

  • agree with (people, opinions)—The women who were polled agreed with the judge.

  • annoyed at or with (a person)—The physician was annoyed at her for the interruption.

  • annoyed by (something)—The physician was annoyed by the constant interruptions.

  • assist at (an event)—He assisted at the service.

  • assist with (someone or something)—Mr. Nguyen assisted with the refreshments and the flowers.

  • contend for (a position, a prize)—The candidates have contended for the office twice.

  • contend with (an obstacle)—The candidate has to contend with his lack of personal charm.

  • depart for ( not to, a destination)—They depart for Canada tomorrow.

  • depart from (a destination, a tradition)—They departed from their routine today.

  • grateful for (a benefit)—I am grateful for my musical talent.

  • grateful to (a person)—I am grateful to you for the help.

  • impatient at (a delay)—They were impatient at having to wait so long.

  • impatient for (a result)—We are impatient for an answer from the administration.

  • impatient with (a person)—He was impatient with the clerk.

  • part from (leave)—I parted from the group early this year.

  • part with (a possession)—I parted with the Volvo reluctantly.