今日は: good day, good afternoon, hello

today, this day / nowadays

Same as こんにち above

good day, good afternoon: a Japanese greeting used in the daytime

(archaic) (as for) today

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

What? What did you say?

whatchamacallit, X

what

What?, Huh?