if

Meanings

1. 1
   conj

   Supposing that, assuming that, in the circumstances that; used to introduce a condition that may be (or prove to be) either true or false.

   If crossing the road, make sure you look both ways.

2. 2
   conj

   Supposing that; used with past or past perfect subjunctive to indicate a counterfactual or hypothetical condition.

   If she hadn't told me, I wouldn't know.

3. 3
   conj

   Considering the fact that; given that; introducing a condition that is known to be true.

   The drain's blocked — and if the drain's blocked, the water won't flow.

4. 4
   conj

   When; whenever; every time that.

   If you heat water to 100° C, it boils.

5. 5
   conj

   Although; used to introduce a concession; may..but.

   He was a great friend, if a little stingy at the bar.

6. 6
   conj

   Whether; used to introduce a noun clause, an indirect question, that functions as the direct object of certain verbs.

   I don't know if I want to go or not.

7. 7
   conj

   Introducing a relevance conditional; in case.

   I have leftover cake if you want some.

8. 8
   conj

   While; used to introduce a contrast.

   If his Russian was music, his English was murder.

Etymology

From Middle English if, yif, yef, from Old English ġif (“if”), from Proto-West Germanic *jabu, *jabē, from Proto-Germanic *jabai (“when, if”). Cognate with Scots gif (“if, whether”), Saterland Frisian af, of (“if, whether”), West Frisian oft (“whether”), Dutch of (“or, whether, but”), Middle Low German ef, if, af, of ("if; whether"; > German Low German of), German ob (“if, whether”), Icelandic ef (“if”).