IPA: //ˈpoʊstˈmɪd.naɪt//
KK: /ˈpoʊstˈmɪdnaɪt/
Referring to the time that occurs after midnight, typically before the early morning hours.
The party continued well into the postmidnight hours, with music and laughter filling the air.
Postmidnight → It is formed from "post-" (meaning after) and "midnight" (from Old English "midniht", meaning the middle of the night). The word "postmidnight" refers to the time after the middle of the night.
Think of 'after' ('post-') the 'middle of the night' ('midnight') — that's what postmidnight means.