The most popular searches in 2010 on Cambridge Dictionaries Online (CDO) show that idioms and slang held the key to learning English as a second language.
Some of the top 2010 idiom and slang searches on CDO were:
'Eat your heart out'
CDO definition: If someone says eat your heart out followed by the name of a famous person, they are joking that they are even better than that person.
'Plus ça change'
CDO definition: The more things change, the more they stay the same. Used when a change does not result in an improvement in a situation.
No mean feat
CDO definition: A great achievement.
'Having said that'
CDO definition: Despite what has just been said.
'Law and order'
CDO definition: When the laws of a country are being obeyed, especially when the police or army are used to make certain of this.
'Right you are'
CDO definition: Said to show that you understand and agree.
'Strike a balance'
CDO definition: If you strike a balance between two things, you accept parts of both things in order to satisfy some of the demands of both sides in an argument, rather than all the demands of just one side.
'Catch a few rays'
CDO definition: to stay outside in the sun for a period of time.