An exclamation of surprise.

(idiomatic) An informal greeting. / (idiomatic) Expression of concern, asking for an explanation

(idiomatic, rhetorical question) Used to express surprise at an unlikely outcome.

An informal greeting.

Euphemistic form of what the fuck.

Alternative form of what time is it

(Britain, colloquial, dated) An exclamation of greeting, summons, or surprise.

(idiomatic) used to add emphasis to "what" when beginning question.

Used other than figuratively or idiomatically: see what, is, the, difference. / (idiomatic) The difference does not matter; so what?

(informal) Speculation as to what might have happened if something else had happened earlier.