Definitions
1.nounAn uncertainty, possibility, condition, doubt etc.
2.conjunctionSupposing that, assuming that, in the circumstances that; used to introduce a condition or choice."If it rains, I shall get wet."
3.conjunctionIn the event that a statement is true (a programming statement that acts in a similar manner)."If A, then B, else C."
4.conjunctionSupposing that; used with past or past perfect subjunctive indicating that the condition is closed."I would be unhappy if you had not talked with me yesterday."
5.conjunctionSupposing that; given that; supposing it is the case that."If that's true, we had better get moving!"
6.conjunctionAlthough; used to introduce a concession."He was a great friend, if a little stingy at the bar."
7.conjunction(sometimes proscribed) 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."
8.conjunction(usually hyperbolic) Even if; even in the circumstances that.
9.conjunctionIntroducing a relevance conditional."I have leftover cake if you want some."