(archaic) If; if it happen (that); supposing that.

(Britain) Ellipsis of if the cap fits, wear it.

Leave something alone; avoid attempting to correct, fix, or improve what is already sufficient (often with an implication that the attempted improvement is risky and might backfire).

(informal, chiefly law) In the event that the thing being discussed comes to pass.

(archaic) If.

(archaic) Alternative form of an if

(UK, finance) Initialism of independent financial adviser.

(idiomatic) If need be; if there is a need.

(idiomatic) Used to suggest or state tentatively that something may be the case (often the opposite of something previously implied).

Alternative form of if you lie down with dogs, you get up with fleas