Longman Dictionary of Contemporary English - if

~1 conjunction 1 used to talk about something that might happen  (What can you do if your child behaves badly in a public place? | If you don't leave now I'm calling the police. | We can always get a taxi if there's a problem with the car. | if by any chance)  (If by any chance Peter should phone, can you tell him that I'll talk to him later? | if not)  (I think there's a train at midday. If not you'll have to wait till 12.30.) 2 used when you are talking about something that always happens in a particular situation  (If I go to bed late I feel dreadful in the morning. | Plastic will melt if it gets too hot.) 3 even if although something is true or something happens  (Even if I did lose a stone, I still wouldn't look skinny.) 4 used to mean `though', when you are describing someone or something that you like  (He's a pleasant child, if a little spoiled.) 5 used like `whether' when asking or deciding whether something is true or will happen  (I rang them to see if I could cancel the appointment. | Ask him if he'll lend me some money. | I wonder if John's got home yet.) 6 used when saying that you are surprised, upset, angry etc that something has happened or is true  (I'm sorry you took it that way. | I don't care if he is my brother. He's still an idiot.) 7 if I were you used when giving advice and telling someone what you think they should do  (If I were you I'd jump at the chance of a job like that) 8 it isn't as if.../it's not as if... used when saying that you do not understand why someone is doing something  (I can't think why they're being so mean. It's not as if they're short of money.) ~2 n 1 ifs and buts BrE ifs, ands, or buts AmE if you do not want any ifs and buts, you want someone to do something quickly without arguing  (No ifs and buts - just make sure the job is done by tomorrow!) 2 and it's a big if used to say that something is not likely to happen  (We can do it if, and it's a big if, we get the money.)