Even if you speak a foreign language fluently, you still can't be sure you know everything about it. And from time to time we come across the words which seem so familiar and "native" to us, but which we are not able to understand while they are used in colloquial speech. For example, let's consider a very simple and common word 'heat'. We got used to comprehending it as "the quality of being hot, or how hot something is", or at least "the energy that is produced when the temperature of something changes". But that is not all. Study these examples: - Who tripped the heat off about me?! (here 'heat' means 'police', 'police officers')
- In the first heat I was the second. (in this case 'heat' denotes 'a game or race at the start of a competition')
- I feel heat after this awful pizza! (and again 'heat' doesn't mean 'hot'! The real meaning is 'bitter taste')
- Yeah, I got my heat on me all the time! (Any guesses? 'Heat' is a 'gun, firing arm')
- There is a lot of heat on James right now. (This means that James is under a lot of pressure to do something)
And this is just one tiny example of how large and diverse the meaning of a word can be! This fact makes a learner feel at a loss... But don't lose heart =) It will be good if some of you share other examples with each other in order to be more linguistically competent. 
