det

• (interrogative) Which, especially which of an open-ended set of possibilities.
  "What colour are you going to use?"
• (indirect interrogative) Which.
  "I wonder what colour he is going to use."
• (relative) Any ... that; all ... that; whatever.
  "He seems to have lost what sense he had."
• 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'.
  "What nonsense!"

pron

• (interrogative) 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."
• (fused relative) That which; those that; the thing(s) that.
  "He knows what he wants and what to do to get it."
• (fused relative) Anything that; all that; whatever.
  "I will do what I can to help you."
• (relative, nonstandard) That; which; who.
  "Look! It's that bloke again what was 'ere yesterday!"

adv

• (interrogative) In what way; to what extent.
  "What does it matter?"

intj

• (British, colloquial, dated) 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?"