if

conjunction

1. Supposing that, assuming that, in the circumstances that; used to introduce a condition or choice.

- If it rains, I will get wet.

2. Supposing that; used with past subjunctive indicating that the condition is not fulfilled.

- I'd prefer it if you took your shoes off.

3. Although; used to introduce a concession.

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

4. (computing) In the event that a statement is true (a programming statement that acts in a similar manner).

- If A, then B, else C.

5. Whether; used to introduce a noun clause as the object of certain verbs.

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

6. (usually hyperbolic) Even if; even in the circumstances that.

noun

1. (informal) An uncertainty, possibility, condition, doubt etc.