(interrogative) Which, especially which of an open-ended set of possibilities.
(indirect, interrogative) Which.
(relative) Any ... that; all ... that; whatever.
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'.
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'.

(interrogative) Which thing, event, circumstance, etc.: used in asking for the specification of an identity, quantity, quality, etc.
That which; those that; the thing(s) that.
Anything that; all that; whatever.
(nonstandard, relative) That; which; who.

(interrogative, not-comparable) In what way; to what extent.
(not-comparable) 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 do you want? An abrupt, usually unfriendly enquiry as to what a person desires.
(British, abbreviation, alt-of, clipping, colloquial, dated) Clipping of what do you say?, used as a type of tag question to emphasise a statement and invite agreement, often rhetorically.
What did you say? I beg your pardon? This usage is often considered impolite, with the more polite "Pardon?" or "Excuse me?" preferred.
Indicating a guess or approximation, or a pause to try to recall information.

(obsolete, uncountable) Something; thing; stuff.
(countable) The identity of a thing, as an answer to a question of what.
(countable) Something that is addressed by what, as opposed to a person, addressed by who.

(Manglish, Singlish) Emphasizes the truth of an assertion made to contradict an evidently false assumption held by the listener.
(Manglish, Singlish) 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”.
(Manglish, Singlish) Used after a direct assertion to reinforce a disagreeing opinion.