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What springs to mind when you see these images?  Click here when you have thought of 6 expressions.

bite the bullet ears cake
both ends cat leg pull 

There are two important characteristics of the expressions in black.  What are they?
Click here when you have an answer.



An early definition of an idiom comes from the linguist and teacher Henry Sweet (a major influence in the Reform Movement's reaction to grammar-translation approaches, incidentally).  He stated:

The meaning of each idiom is an isolated fact which cannot be inferred from the meaning of the words of which the idiom is made up.
(Sweet, 1889:139)

Since Sweet's time, the area has been continually revisited by researchers interested in finding out what constitutes idiomaticity in languages and how the various types of idiom can be classified and analysed.  What we have ended up with is a confusing muddle of terms, definitions and classifications which is, to say the least, unhelpful.  You may, for example, come across any or all of the following terms if you research this area:

figurative idioms or non-compositional metaphors to refer to fact that we can often find a connection between figurative, idiomatic and literal meaning.  It is for example, just possible to figure out what bite the bullet might mean with some knowledge of pre-anaesthetic surgery.  Ditto, perhaps, with have an ace up one's sleeve
binomials to refer to expressions such as time and again, Ladies and Gentlemen which occur as pairs of words, often with a fixed ordering
fixed expressions to refer to idioms which are truly fixed such as an open and shut case
semi-fixed expressions to refer to idioms where some flexibility is allowed.  For example, you can throw in the towel but also throw in the sponge, both meaning surrender, and both derived from boxing
lexicalised expressions to indicate that the expression functions as a single lexeme.  For example, kick the bucket actually just functions as the verb die
opaque expressions emphasising the fact that is often not possible to work out metaphoric meaning from literal meaning as it is with figurative metaphors.  For example, chew the fat
frozen collocations emphasising the fixedness characteristic of some idioms such as a can of worms
restricted collocations referring to those which allow some flexibility but only within a limited range.  For example, you can be a big/large fish in a small/little pond
semi-idioms to refer to anything which seems like an idiom, insofar as it acts like a single word, but is not completely opaque and fixed.  One part of the expression has a figurative meaning not found elsewhere but the other part is 'normal' as in expressions such as pay attention or foot the bill

It is not the suggestion here that such refinements are useless or deliberately confusing but we are interested in classifications which will be useful to us as English-language teachers rather than research linguists so this guide will focus on two the central characteristics of idiomatic language: fixedness and opacity (or non-compositionality, if you prefer).
This will be at the expense of some precision so if you are looking for more, there are references at the end to on-line, more scholarly articles that you may want to read.



This is not an on-off characteristic.  Some idioms are more fixed than others, some are very flexible.  Here's a cline for you to see what's meant.  Where would you put the idioms on right in the cline on the left (if idioms they actually are)?  Click on the image for some comments when you have an answer.

fixedness cline through thick and thin
hammer and sickle
aid and abet
have a blast
hit the sack
off one's rocker
call it a day
assets and liabilities
left, right and centre
life or death
back to the drawing board
cut corners
put all your eggs in one basket
torrential rain
wouldn't be caught dead
miss the boat
make the grade
make the beds
raining cats and dogs

Opacity or non-compositionality

Again, there's a cline because there are levels of opacity and transparency.  The image below separates them into those whose meaning is obvious (literal), those where it can be deduced (figurative uses) and those which are wholly opaque.
As you did above, locate these expressions on the right somewhere on the cline on the left and then click the image for a commentary.

transparency  barking up the wrong tree
a bitter pill to swallow
by the skin of one's teeth
bread and circuses
kiss and tell
heads or tails
spick and span
holding all the aces
at a snail’s pace
a dime a dozen
bite off more than one can chew
cut the mustard
bob and weave
under the weather
hot and bothered
research and development
come rain or shine
Tom, Dick and Harry


The relationship between fixedness and opacity

There is a tendency for these two characteristics to rise and fall together.  In other words, the more fixed and inflexible the expression, the more likely it is to be opaque in meaning and vice versa.

We can find low fixedness with some expressions but they are likely to be quite literal in meaning.  For example, as old as ... can be followed by a number of expressions (God, the hills, Noah etc.) but opacity is also low.
Similarly, strong collocations such as a pronounced accent are not firmly fixed (we can have strong, broad etc. as the adjective with roughly the same meaning) but they are usually easy to understand (if not to learn).

On the other hand, an expression such as off one's rocker has quite high fixedness (there's only one conventional alternative to rocker, trolley) and it is also quite high in opacity.  Extreme cases of fixedness are also, often, extreme cases of opacity.  Expressions such as let the cat out of the bag are both opaque and fixed as are binomials such as helter-skelter.

There are, nevertheless, instances, especially with binomials, of low opacity and high fixedness.  In other words, they always occur together and in the same order but are straightforward to understand.  Examples are:
    here and there
    hand in hand
    dead and buried

The moral?
Whenever we find a highly opaque expression, the way to bet is that it is also firmly fixed.  The reverse is not always true.
Here's a graphical representation of that.  Before teaching idioms, it is worth 5 minutes of the planning time to consider where in the matrix the target language items fall.

parrots three

Binomials and trinomials

Because these are so common in English, they merit a short section to themselves.
Here's a selection.  Notice that some are literal (apples and oranges etc.), some are figurative (the chicken or the egg etc.) and some are wholly opaque (milk and honey etc.)  Some also contain words found nowhere else.
When two nouns are joined, the resulting expression is usually singular.  The order is usually fixed.
Fuller lists with some doubtful inclusions are available via a web search.

joined with and or or/neither ... nor

above and beyond
airs and graces
alive and kicking
an arm and a leg
apples and oranges
assault and battery
back and forth
ball and chain
beck and call
bells and whistles
bits and bobs
bow and arrow
by and large
cat and mouse
cut and run
dead and buried
divide and conquer
down and out
each and every
eyes and ears
far and wide
fast and loose
fire and brimstone
forever and a day
free and clear
hale and hearty
hard and fast
hearts and minds
here and now
home and dry
horse and carriage
intents and purposes
knife and fork
law and order
lo and behold
loud and clear
man and boy
milk and honey
nook and cranny
nuts and bolts
odds and ends
pure and simple
room and board
all or nothing
better or worse
the chicken or the egg
day or night
dead or alive
do or die
fight or flight
(neither) fish nor fowl
(come) hell or high water
(neither) here nor there
hit or miss
kill or cure
kill or be killed
love nor money
make or break
more or less
rain or shine
sink or swim
sooner or later
take it or leave it
seek and destroy
short and sweet
sick and tired
slash and burn
smash and grab
snakes and ladders
stand and deliver
supply and demand
sweetness and light
tables and chairs
tar and feather
tea and crumpets
thunder and lightning
to and fro
tooth and nail
touch and go
trial and error
up and about
vim and vigour
wait and see
wine and roses

with rhymes or similar sounds

box and cox
chalk and talk
double trouble
even Stevens
high and dry
hire and fire
hither and thither
huff and puff
hustle and bustle
meet and greet
name and shame
near and dear
odds and sods
out and about
time and tide
town and gown
use it or lose it
wear and tear
wine and dine
yea or nay

with reduplication

again and again
all in all
around and around
arm in arm
back to back
bit by bit
bumper to bumper
by and by
cheek to cheek
closer and closer
coast to coast
day to/ by day
elbow to elbow
end to end
dog eat dog
from ear to ear
an eye for an eye
eye to eye
face to face
hand in hand
head to head
heart to heart
higher and higher
horror of horrors
less and less
little by little
lower and lower
man to man
more and more
mouth to mouth
neck and neck
never say never
nose to nose
on and on
out and out
over and over
round and round
shoulder to shoulder
side by side
side to side
step by step
strength to strength
through and through
time after time
(from) time to time
two by two
toe to toe
wall to wall
for weeks and weeks
woman to woman


There are fewer of these.  Examples include:

beg, borrow or steal
blood, sweat and tears
eat, drink, and be merry
ear, nose and throat
guns, germs, and steel
healthy, wealthy, and wise
here, there and everywhere
hook, line and sinker
gold, silver, and bronze
hop, skip and jump
judge, jury and executioner
left, right and centre
lock, stock and barrel
nasty, brutish and short
planes, trains, and automobiles
ready, willing and able
reading, writing and arithmetic
red, white and blue
sex, drugs, and rock 'n' roll
sugar and spice and everything nice
tall, dark and handsome
Tom, Dick and Harry
shake, rattle and roll
this, that, and the other
way, shape, or form
win, lose, or draw


Many binomials, especially those without a connecting conjunction, are conventionally hyphenated so we get helter-skelter, willy-nilly, harum-scarum and so on.
Others are only hyphenated when they are used adjectivally so we get, for example:
    It's a question of law and order
    The price is subject to the influence of supply and demand

etc., because these are being used as nouns, but we have:
    This is a law-and-order issue
    It's a supply-and-demand influence

etc., because these are adjectival uses.
Trinomials exhibit the same phenomenon.

Fixed similes

Unlike metaphors, similes explicitly compare two items, usually, in English, with the as ... as formulation.
A number of these constitute a kind of idiom although in almost all cases they are a) fixed and b) often (but not always) quite literal and transparent in meaning.  They include items such as:
    as blind as a bat
    as cool as a cucumber
    as fit as a fiddle
    as good as gold
    as old as the hills
    as keen as mustard
    as regular as clockwork
    as right as rain
    as safe as houses
    as thin as a rake



Most idiomatic language is stylistically informal and inappropriate in a number of situations.  Idioms are used extensively in informal speech and writing (especially in newspapers), however, so a knowledge of common ones is very helpful for learners of English.  Unfortunately, there are, by some estimates, 25,000 of them in English.
In more formal contexts, idioms will often be avoided so we are unlikely to find, for example:
    Buckingham Palace announced that the Queen is under the weather
    The government negotiators are reluctant to open a can of worms, said the White House spokesman.
Learners of the language can be tempted to overuse idiomatic language in situations where it is not appropriate or they can get the meaning just slightly wrong and produce, e.g.:
    *I'll do it willy-nilly
    *The government isn't cutting the mustard for it

The same considerations of grammar and form apply here as they do in the teaching of any lexis.
It is important to make sure, then, that idiom presentation is set in an appropriately context and that word class is considered along with aspects of transitivity and so on.


Teaching idiomatic language

Too often, in course books and study guides, idioms and idiomatic language are relegated to peripheral 'Useful phrases' boxes and then ignored.  That's a great pity as it is almost impossible to become fluent in English without acquiring a fair number of idiomatic expressions.  In fact:

Most students are very interested in learning idiomatic language.  They recognize it as an area in which they have difficulties, and appreciate systematic instruction.
(Irujo, 1986: 242)

There's nothing mysterious about this.  We have to make the same judgements that we make when teaching lexis of any sort.  In other words, we must consider appropriacy and style, range, learnability, frequency and so on.  For more, see the guide to teaching lexis.

However, idioms and idiomatic language have some characteristics that make certain approaches more worthwhile and productive.

  • Context
    Idioms occur more naturally in informal story-telling language so that's a good place to situate them.  Context will also help learners appreciate issues of style and co-text will often disambiguate meaning successfully.
  • Illustrations
    Because idioms are so picturesque, it makes it comparatively easy to link them to illustrations (see the introduction to this guide for examples).
  • Figurative meaning
    Group and pair-work to decipher figurative meaning is helpful because people see different things in language and have different mental metaphors so they can help each other significantly.  Obviously, the more transparent the meaning is, the less hard the expression will be to understand and learn.
  • Retelling stories
    Retelling exercises can be a powerful way of consolidating idiomatic language as can dialogue writing and creative story writing.
  • Translation
    Idioms rarely translate exactly between languages but it is surprising how similar concepts are encoded in idiomatic language.  For example, the expression it cost an arm and a leg is rendered in Spanish with something like it cost an eye of your face and in German, a hook in the matter means there's a fly in the ointment.  All languages exhibit a rich and picturesque range of metaphorical meaning.  It can be educational, interesting and fun to compare how meanings are encoded in various languages and that, too, can help retention.
    Here are some examples for fun.  Can you match the English idioms on the left to their equivalents in other languages on the right?  Click on the image when you have an answer.

    idiom translation
    You can, of course, get your learners to make up quizzes like this.

More teaching ideas can be found in Irujo (1986)

In the section for learners on this site, there are some exercises to do with idioms and binomials.  Check the exercise index under vocabulary for more.

There is a very short test on some terms to help you recall all this.

Related guides
synonymy for more on how this and related areas work with more on similes (fixed and otherwise)
semantics for a theoretical guide to meaning
teaching lexis for some practical ideas
collocation for more on this form lexical relationship

Barkema, H, 1996, Idiomaticity and terminology: a multi-dimensional descriptive model, Blackwell Publishing Ltd., Studia Linguistica, Volume 50, Issue 2, pp. 125-160
Benor, S.B & Levy, R, no date, The Chicken or the Egg? A Probabilistic Analysis of English Binomials, available from http://www.pdfmanuale.com/file/9GW/the-chicken-or-the-egg-a-probabilistic-analysis-of-english.html [accessed January 2015]
lrujo, S, 1986, A piece of cake: learning and teaching idioms, English Language Teaching Journal, 40 (3) pp. 236-242, Oxford: Oxford University Press
Moreno, R.E.V, no date, Idioms, Transparency and Pragmatic Inference, available from http://www.phon.ucl.ac.uk/publications/WPL/05papers/vega_moreno.pdf [accessed January 2015]
Sweet, H, 1889, The practical study of languages, London: Oxford University Press (Reprinted in 1964)