Longman Dictionary of Contemporary English - hap'orth

happen ~ v 1 if an event or situation happens, it exists and continues for a period of time, especially without being planned first  (The accident happened early on Tuesday morning. | No one knew who had fired the gun - it all happened so quickly. | It's impossible to predict what will happen in Cambodia in the next few months. | sth is bound to happen (=something is certain to happen) | sth happens all the time (=something happens often))  (This kind of thing happens all the time. | whatever happens)  (I'll look after you whatever happens.)  (- see occur, - see also happen to) 2 to be caused as the result of an event or action  (She pressed hard on the brake pedal, but nothing happened. | What would happen if your parents found out?) 3 to do or have something by chance  (happen to do sth)  (I happened to meet her on my way home. | it happens that (=by chance, it is true that))  (It happened that the new person in the office was the woman he had met at Gail's party.) 4 sb/sth happens to be used when telling someone something in an angry way, especially because you are annoyed by something they have just said  (That woman you're talking about just happens to be my wife!) 5 what's happening? a) used to ask what people are doing, or what the situation is, especially when you are worried or annoyed about this  (Hey, what's happening? Why has the light gone out? | What's happening here, then? You'd better stop that!) b) AmE used when you meet someone you know well, to ask them how they are and what they have been doing  (Hey Carl, what's happening, man?) 6 what's going to happen/what happens/what will happen...? used to ask what the result of something will be  (What happens if you push this button? | What's going to happen when she finds out?) 7 whatever happens used to say that no matter what else happens, one thing will certainly happen  (Whatever happens in the future, we wish you well.) 8 as it happens used to tell someone something that you think will be useful for them, and is connected with what they have just been talking about  (As it happens I know someone who might be able to give you some advice.) 9 it (just) so happens that used to tell someone about something interesting that is connected with what you have just been talking about  (Now, it just so happens that he had been to the same school as me.) 10 these things happen used to tell someone not to worry about a mistake they have made, an accident they have caused etc  (These things happen)  (don't give it another thought.) 11 anything can happen used to say that it is impossible to know what will happen  (Anything can happen in a race like that.) 12 see what happens used to say that if someone does not know what the result of doing something will be, they should try it and find out  (Just turn the switch and see what happens. Is it working?) 13 what usually happens is/what tends to happen is used to say what usually happens in a particular situation  (What tends to happen is we meet up for a drink, then go for something to eat.) 14 you don't/do you happen to...? used politely to ask someone if they have or know something  (You don't happen to know his address, do you?)  (- see also accidents will happen accident (5)) happen by phr v AmE to find a place by chance happen on sb/sth, happen upon sb/sth phr v to find something or meet someone by chance  (They were strolling through the old part of the town when they happened on a tiny Greek restaurant.) happen to sb/sth phr v 1 if an event happens to someone or something, they are involved in it and affected by it  (A funny thing happened to me on my way home last night.) 2 whatever happened to a) used when you want to know where someone is and what they are doing, because it is a long time since you saw them  (Whatever happened to Kate Scott?) b) used when saying that something such as an idea, quality, or custom seems to have disappeared or been forgotten about  (Whatever happened to the idea of the paperless office?)