what

Which, especially which of an open-ended set of possibilities.

• What colour are you going to use?
• What time is it?
• What kind of car is that?

Which.

• I wonder what colour he is going to use.
• I know what colour I am going to use.
• That depends on what answer is received.

Any ... that; all ... that; whatever.

• He seems to have lost what sense he had.
• What money I earn is soon spent.

Emphasises that something is noteworthy or remarkable in quality or degree, in either a good or bad way; may be used in combination with certain other determiners, especially 'a', less often 'some'.

• This shows what beauty there is in nature.
• You know what nonsense she talks.
• I found out what a liar he is.

Used to form exclamations indicating that something is remarkable, in either a good or bad way.

• What nonsense!
• Wow! What a speech.
• What beautiful children you have.

Which thing, event, circumstance, etc.: used in asking for the specification of an identity, quantity, quality, etc.

• Hammer in that nail — What with? I didn't bring my set of tools.
• What is your name?
• My kids set the neighbor's cat on fire. — They did what?

That which; those that; the thing(s) that.

• He knows what he wants and what to do to get it.
• What is amazing is his boundless energy.
• And, what's even worse, I have to work on Sunday too.

Anything that; all that; whatever.

• I will do what I can to help you.
• What is mine is yours.

That; which; who.

• Look! It's that bloke again what was 'ere yesterday!

In what way; to what extent.

• What does it matter?
• What do you care?

Used before a prepositional phrase to emphasise that something is taken into consideration as a cause or reason; usually used in combination with 'with' (see what with), and much less commonly with other prepositions.

An expression of surprise or disbelief.

• What! That’s amazing!

What do you want? An abrupt, usually unfriendly enquiry as to what a person desires.

• What? I'm busy.

Clipping of what do you say?, used as a type of tag question to emphasise a statement and invite agreement, often rhetorically.

• It’s a nice day, what?

What did you say? I beg your pardon? This usage is often considered impolite, with the more polite "Pardon?" or "Excuse me?" preferred.

• — Could I have some of those aarrrrrr mmmm ... — What?

Indicating a guess or approximation, or a pause to try to recall information.

• I must have been, what, about five years old.

Something; thing; stuff.

The identity of a thing, as an answer to a question of what.

Something that is addressed by what, as opposed to a person, addressed by who.

Emphasizes the truth of an assertion made to contradict an evidently false assumption held by the listener.

• Pitch contour: low [wʌt˩], low-dipping [wʌt˨˩]
• — Sian sia, nearby here don’t have library. — The National Library is a five-minute walk from here what, no meh?

Used to invite agreement or acknowledgment when something is assumed to be straightforward or already obvious to begin with; similar in function to “right?” and “as you know”.

• Pitch contour: low [wʌt˩], low-dipping [wʌt˨˩]
• If it doesn’t get sunlight, it won’t grow what, so you should consider moving it closer to the window.

Used after a direct assertion to reinforce a disagreeing opinion.

• Pitch contour: low [wʌt˩], low-dipping [wʌt˨˩]
• The lava cakes are not that bad what.