Initialism of interactive fiction. / Initialism of impact factor. / (biochemistry) Initialism of intermediate filament. / (electronics) Initialism of intermediate frequency.

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

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

Not unless; used to introduce a necessary condition.

(dated, formal) please

An unlikely but necessary condition.

Used to introduce a suggestion or proposal for a future event. / Used to introduce a speculation about a future event.

Used other than figuratively or idiomatically: see if, only. / (idiomatic) I wish that; signifies a wish or desire for the present or the future.

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

(idiomatic) A situation where either choice results in a negative outcome.