Idioms are important cultural elements of all languages, and they also make our speech more colourful. It's fun to study idioms; however, it is true that they can cause some misinterpretation because translating them word by word will not make much sense in your language.
In short, an idiom is a combination of words that has a figurative meaning. For example, “cold feet” as an idiom doesn't have anything to do with the temperature of your feet; it actually means, “a sudden nervousness, or a lack of confidence before a big event.” Think of an idiom in your language that expresses the same idea!
According to Wikipedia, there are at least twenty-five thousand idiomatic expressions in the English language. Today we will look at ten body idioms and their meanings:
1. Break a leg! – to wish good luck
This idiom is used in the theatre by performers who think that wishing “good luck” will actually bring bad luck. People also say it outside theatres to express the same idea.
- Today's your exam, right? Break a leg!
2. Skin and bones – very thin / more than slim, perhaps because of a lack of nutrition
This idiom refers not only to people but also animals. The opposite would be fat or overweight.
- Tom never gains weight. He is all skin and bones.
- My neighbour's cat is skin and bones, I don't think she feeds him regularly.
3. To have one's head in the clouds – daydreaming
This describes someone who is unrealistic about something and unaware of what is going on. The opposite meaning would be to have one's feet on the ground.
- You've got your head in the clouds if you think you can become a talented musician without practising.
4. To keep an eye on – to take care of
This could mean to monitor or to give protection. You can keep an eye on things and people.
- Could you keep an eye on dinner and the baby while I answer the door?
5. A sweet tooth – a love of sugar or sweets
If you enjoy eating sweet things, you have a sweet tooth.
- I see Lucy eating chocolate every day. She must have a sweet tooth.
6. To cost an arm and a leg – to be very expensive
You can think of it this way: the loss of any body part would be a high price to pay for something, therefore you use it to mean a lot of money.
- Max bought a bike, but it cost him an arm and a leg.
7. To give a hand – to help (someone) do something
This is especially related to physical work.
- I can give you a hand when you redecorate your room.
8. Behind someone's back – to do something without them knowing
This is done secretly and in a way which can be unfair.
- My daughter is very sad because she discovered that her best friend had spoken behind her back.
9. Elbow grease – hard scrubbing; working hard at manual labour
It humorously suggests that sometimes one can achieve a better result through human energy and hard work, rather than by using special products.
- Our grandmother never used chemical cleaning products, only elbow grease.
10. Itchy feet – a strong desire to travel
- I have lived in Lisbon for 20 years but I'm getting itchy feet; there are so many countries I want to visit!
Remember that idioms are used informally! You shouldn't change articles or words because the idiom will lose its meaning if you do so. Although idioms are said not to be strictly necessary for a language learner, they can help you to understand how English is used on a daily basis. While learning a language and living in a foreign country, you will gradually pick up phrases that are indeed uncommon and often not included in the language books. This is natural and demonstrates how language evolves over time.
Living in Portugal, I have learned the importance of street language, slang, and the use of idioms. Although there are dictionaries that detail the use of calão (slang), the meanings can often only be understood in a particular situation. In England, there is a prominent use of idioms among native speakers; all you have to do is go to the pub and use your lords and peers (which is Cockney rhyming slang for ears)! :)
There are many books and websites available for learning idioms. I recommend checking the BBC website, where there is a section called “The English We Speak”. It highlights one idiom per day.