idioms

Idioms

What is an idiom?
An idiom is a particular group of words with a special meaning which is different from the meanings of the individual words.
 
Idioms usually have a fixed word order
Although certain small changes can be made in idiomatic expressions (see below: Using idioms) you cannot usually change the words, the word order, or the grammatical forms in the same way as you can change a non-idiomatic expression.

For example:
The answer's easy can be changed to The answer's simple. But in the expression It's (as) easy as pie, the word simple cannot be used.

She likes cats and dogs can be changed to She likes dogs and cats. But in the expression It's raining cats and dogs (= raining hard), the word order is unchangeable.

He almost bought the farm can be a literal expression meaning, for example, 'he almost purchased some land for farming.' In this case, the farm can be replaced by a pronoun: He almost bought it, or the verb can be used in the passive form: The farm was almost bought. However, He almost bought the farm can also be a fixed idiomatic expression meaning 'he almost died.' When this expression is used as an idiom, no word changes are possible.
 
Idioms have a special meaning
Sometimes the meaning of an idiom can be guessed from the meaning of one of the words:
to rack your brains (= to think hard; something to do with brains)
to live in the lap of luxury (= to have a lot of very expensive things; something to do with luxury)

Usually, however, the meaning of an idiom is completely different from any of the separate words:
She was over the moon about her new job (= she was extremely happy).
The test was a piece of cake (= the test was very easy).

Sometimes an expression can have two meanings, one literal and one idiomatic. This happens most often when the idiomatic expression is based on a physical image:
a slap in the face (= a physical hit to the face; an insult or an action which seems to be aimed directly at somebody)
to keep your head above water (= to prevent yourself from sinking into the water; to be just barely able to live on your income, or to be just barely able to go on with life, work etc.)
 
Recognizing idioms
How do you recognize an idiom? It is sometimes difficult to know whether an expression is literal or idiomatic, so it is useful to remember some of the most common types of idioms.
 
Pairs of words
touch-and-go
high and dry
in black and white
the birds and the bees
(Note that the word order in these pairs is unchangeable.)
 
Similes
(as) blind as a bat
(as) large as life
(as) mad as a hatter
(as) old as the hills
 
Phrasal verbs
chicken out of sth
come across sb/sth
nod off
put up with sb/sth
 
Actions which represent feelings
look down your nose (in scorn or dislike)
raise your eyebrows (in surprise, doubt, displeasure, or disapproval)

These idioms can be used by themselves to express feelings even when the feeling is not stated. For example There were a lot of raised eyebrows at the news of the governor's resignation just means 'everyone was very surprised.'
 
Sayings
Many sayings are complete sentences. Remember, however, that sayings are not always given in full:

We'll probably win the tournament, but we shouldn't count our chickens yet. (The speaker is warning that people should not be too confident about what will happen.) The full saying is: Don't count your chickens before they hatch.

They may never accept our proposal. You can lead a horse to water, you know. (The speaker says that no matter how much effort they put in, they may not get the results they want.) The full saying is: You can lead a horse to water, but you can't make him drink.

I didn't say you were a liar, but hey, if the shoe fits. (The hearer previously thought the speaker had accused him of being a liar. The speaker had not said this, but believes that the hearer is a liar.) The full saying is: If the shoe fits, wear it.
 
Using idioms
Before using an idiom, ask yourself the following questions:
 
How fixed is the expression?
Sometimes certain parts of an idiom can be changed.

Verbs, for example, can often be used in different forms. (Note, however, that they are rarely used in the passive form.)
He caught her eye.
Catching the waiter's eye, he asked for the bill.

In many expressions, it is possible to change the subject pronoun:
He swallowed his pride.
They swallowed their pride.
Janet swallowed her pride.

Someone can usually be replaced by other nouns or pronouns:
jog someone's memory
She jogged my memory.
This photo might jog your memory.

Remember, however, that most idioms are far more fixed than literal expressions, and many cannot be changed at all. (See the Longman American Idioms Dictionary for full details.)
 
Is the style right for the situation?
Many idiomatic expressions are informal or slang, and are only used in informal (usually spoken) language.
Compare:
He said the wrong thing and He put his foot in his mouth. (INFORMAL)
They all felt very depressed and They were all down in the dumps. (INFORMAL)

Some expressions are literary or old-fashioned and are not often used in everyday language except possibly as a joke:
I guess Jen's parents didn't like the cut of my jib. (humorous use of an old-fashioned idiom)