determiner Which, especially which of an open-ended set of possibilities.
What colour are you going to use?
determiner Which.
I wonder what colour he is going to use.
determiner Any ... that; all ... that; whatever.
He seems to have lost what sense he had.
determiner 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.
determiner Used to form exclamations indicating that something is remarkable, in either a good or bad way.
What nonsense!
pronoun 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.
pronoun That which; those that; the thing(s) that.