in the event that
If she phones, let me know
supposing
If you'd listened, you'd know
on condition that
I'll lend you my laptop if you can get it back to me by Friday
whether
She asked if the mail had come
used to introduce an exclamation expressing a wish
If only you'd waited!
If it would only rain!
even if; although
That's an interesting if irrelevant point
used after expressions of emotion: that
I don't care if she is cross!
It's not surprising if you're annoyed
used to introduce expressions, usu in the negative, of surprise, dismay, etc
Blow me if he didn't hand in his notice right there and then
used to suggest tentatively or tactfully that something is or could be the case
It's if anything a bit too colourful
If anything, you ought to apologize
if that is not so
perhaps to the point of being
It was unwise, if not downright idiotic