Kyūjitai form of 補体 (“complement”)

(adverbial particle, dismissive, derogatory) emphasizes disgust, contempt, or otherwise negative feelings of the speaker: whatever

supplement

What? What did you say?

whatchamacallit, X

nothing

what number, how many (used with a counter) / (used with も) many (used with a counter)

What?, Huh?

what / that thing (used in place of words you can't remember at the moment.)

what