Definition of “if” - English Dictionary

“if” in British English

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ifconjunction

uk /ɪf/ us /ɪf/

if conjunction (IN THAT SITUATION)

A2 used to say that a particular thing can or will happen only after something else happens or becomes true:

I'll pay you double if you get the work finished by Friday.
We'll have the party in the garden if the weather's good. If not (= if the weather is not good), it'll have to be inside.
If anyone calls, just say I'll be back in the office at four o'clock.
If she hadn't called, I wouldn't have known.
I wouldn't work for them (even) if they paid me twice my current salary.
We'll deal with that problem if and when it arises.
If disturbed, the bird may abandon the nest, leaving the chicks to die.

although:

They're great kids, even if they can be demanding.
literary It was a hot, if windy day.

B1 every time:

If water is heated to 100°C it turns to steam.
If I don't get enough sleep I get a headache.

used to mean "if it is true that":

I'm very sorry if I've offended you.

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if conjunction (WHETHER)

B1 used to introduce a clause, often in indirect speech, that shows two or more possibilities:

Mrs Kramer called half an hour ago to ask if her cake was ready.
I don't care if he likes it or not - I'm coming!
I was wondering if you'd like to come to the cinema with me this evening?
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if conjunction (REQUEST)

used when you want to make a polite request or remark:

If you'd like to take a seat, Mr Chang will be with you in a moment.
Would you mind if I open/opened (= can I open) the window?
There are, if you don't mind me saying so, one or two problems with this plan.

Grammar

ifnoun [ C usually singular ]

uk /ɪf/ us /ɪf/ informal

something that is not certain or not yet decided:

There's a big if hanging over the project (= it is uncertain whether the project will happen).

Idiom(s)

(Definition of “if” from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

“if” in American English

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ifconjunction

us /ɪf/

if conjunction (IN THAT SITUATION)

used to say that a particular thing can or will happen when, only when, or after something else happens or becomes true:

We’ll have the party in the backyard if the weather’s good.
If anyone calls for me, just say I’ll be back at 4 o’clock.
Would you mind if I opened the window (= May I open it)?

If is also used to talk about the amount or degree of something:

This time of year we get little, if any, rain (= almost none).

If can mean when:

If I don’t have a cup of coffee in the morning, I’m useless.

If can also mean in case it is true that:

I’m sorry if I’ve offended you.
if it weren't for

When you say if it weren't for or also if it hadn't been forsomething, you mean if it were not true or had not happened, the situation would be different:

If it weren’t for your help, we would never have finished in time.

if conjunction (WHETHER)

(used to introduce a clause, often when reporting what someone else said) whether:

Mrs. Kramer called to ask if her cake was ready.

ifnoun [ C ]

us /ɪf/

if noun [ C ] (UNCERTAIN SITUATION)

something that is not yet certain or not yet decided:

The plan contains a lot of ifs.

(Definition of “if” from the Cambridge Academic Content Dictionary © Cambridge University Press)