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

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

Euphemistic form of what the fuck.

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

Said by one friend to another in response to thank you.

An intensive form of what.

(US, idiomatic) Everything that is required.

Used to express regret or disappointment about an unfortunate event or piece of information.

(archaic, colloquial) Of what kind.

(archaic) But what does it matter; notwithstanding.